Without having to go into spoiler territory---
I like your suggestion of
The Mandalorian instead starring Boba Fett,
@KilroywasNOTHere, and it just being a Boba Fett character piece from the start. Din Djarin is nice enough, but he's basically a Fett expy anyway. Cool bounty hunter in cool armour.
You wouldn't even have to lose the radical sect of Mandos we get in the original series. Their existence does make some sense, in that ltra-radical splinter movements would realistically develop in the wake of planetary genocide. Totally hyper-focused on "The Old Ways", which they only sort of half remember, actually, so they just kind of make it up (convincing themselves that they have it all figured out right and proper). It only takes one rabid Death Watch straggler leading a bunch of orphan kids that he indocrinates, and there's your little cult of fanatics.
Anyway, they could play a role in the plot, distrusting Fett because he doesn't follow the Mando ways (as they see them), but at the same time not caring that he's actually a clone of a guy whose Mando creds are contested. To them, anyone who joins up and adheres to "The Way" is a true Mando.
And then you can contrast this with Bo Katan's group, which doesn't care about ultra-traditionalism (and really, they look down on it, seeing that sect as a bunch of obsessive LARP-ers), but who all disdain Boba for "just being a clone", and thus "not a REAL Mandalorian".
The logical trajectory for the series, of course, would be for Boba Fett -- wiser, after his ordeal with the Sarlacc and his time with the Tuskens -- to gradually build up a network of friends and allies, gain the Darksaber, and eventually coming to unite the disparate groups of Mandos under his banner. (Basically, his parental role to Grogu + his role of increasing authority as underworld kingpin = thematic fusion in him becoming the "father figure" to the remaining Mandalorians.)
For all this to work, you'd have to re-arrange quite a few plot points, of course. Such a series would have to start with Boba staggering out of the desert and confronting Cobb Vanth about his armour. (I think we'd first see Cobb, in the armour, before armour-less Boba is subsequently introduced.) As we'll later learn, this all happens shortly after the Tuskens have been slaughtered. Boba knows that Jawas stole and sold his armour, but living with the Tuskens, he didn't care. Now, he's out for revenge.
This whole set-up means it makes a lot of sense that he can communicate with the Tuskens easily. The tribe he allies with was friendly with the tribe Boba joined. He brokers peace between the Tuskens and Mos Pelgo, and together they defeat the Krait dragon. But Boba is visibly weakened at this point.
He gets his armour back. Vanth asks him to stay on, join him in peace-keeping duties. Boba suggests that he means to bring peace to all Tatooine. Vanth realises that Fett means that he's going to take on the Pykes. Vanth thinks this is crazy: the Pykes have basically taken over the whole planet, allying with figures like Bib Fortuna.
Boba admits that he isn't ready for that kind of a fight yet, but that he'll come back stronger than he is now.
After that, he seeks out Greef Karga, who is an old associate. Karga gives him access to a safe bacta tank in between assignments. This gives him easy access to the services of the notorious Boba Fett, while Boba gets to keep his remaining weakness (after the Sarlacc ordeal) a secret. Boba Fett returns to bounty hunting. Much as Season 1 Din, he gets hired to track down Grogu.
We get the flashbacks to Boba's "Tusken years" during his bacta tank sessions during season 1. Maybe Grogu can be compared and contrasted with a Tusken kid that Boba couldn't save from the massacre.
Cara Dune would be far more distrusting Fett initially, because he worked for the Empire. The Imperials would be
more willing to work with him, for the exact same reason.
The traditionalist Mando cult would be interested in having Boba Fett join them, particularly because he never removes his helmet. This initially makes them think he could be just like them. He disabuses them of the notion, saying he keeps the helmet on because it's a symbol. It makes him more feared and respected, when the helmet is the only 'face' people know. Most of the ultra-trad Mandos get angy at this, but the Armourer can then just point out that his reason is, in fact, the exact same reason why this tradition was created in the first place. "You may well be one of us without yet knowing it, Boba Fett."
(And conversely, Bo Katan can later jeer at him about what
she thinks his true motives are: "You just wear the helmet to hide the fact that you share a face with millions of identical clones who died for nothing in a pointless war.")
The introduction of Fennec would have to be a bit different, since she'd be a clear antagonist first, but the Fett would save her life anyway, and convince her to join him. His goal, above all, is to form a group of hard-core allies who can help him fight the Pykes, whom he hates.
Season 1 ends with the big confrontation, where Boba first convinces the ultra-trad Mandos to help him, because even if he is not like them, he is at war against the Empire that killed their world. And ultimately, he even gets Cara Dune to join him, by removing his helmet and asking her to help him save the innocent child from the hands of the Imperials.
We still get the reveal of Moff Gideon having the Darksaber, but I wouldn't just get rid of Werner Herzog's character quite so quickly. I'd instead double down on the notion of there being a group of Imperials who are really "getting the back back together". (On that note, Titus Welliver's character would get a more prominent role, too.)
Season 2 could be much as we know it. Differences would be that Boba Fett knows what Jedi are, and who Luke Skywalker and Ahsoka Tano are, too. But the general trajectory would be the same. The final conclusion would see Boba taking the Darksaber, and then meeting Luke. Presumably while
holding the Darksaber. For a moment, it look like they'll fight... but then they both put their weapons down. And they really talk about Grogu's future. None of that 'no attachments' bullshit. Luke agrees to train Grogu, but Boba is his Space Dad, and Grogu will still regularly be going on journeys with Boba. (But Boba deliberately doesn't want the kid there for his war against the Pykes.)
Boba then returns to Tatooine, and together with Fennec Shand and Cobb Vanth, kills Bib Fortuna and takes over.
Then we get the equivalent of Season 1 of
The Book of Boba Fett, now with 100% fewer flashbacks. That ought to speed up the pace, while giving us more time for Boba to put his new anti-Pyke coalition in place. We start with the Mando-on-Ringworld episode, but now starring Fett. He tries to get the ultra-trad Mandos to join him. They refuse. Vizsla challenges him, and is beaten. The Armourer then says that Fett may be truly worthy, and gives some vague hints about some trial Fett would have to complete. If he does, then that + his ownership of the Darksaber would cause their faction to follow him. (That's all set-up for next season.)
He goes back to Tatooine again, somewhat irritated that he couldn't get these potential allies on board. At this point, the Hutts show up and offer him support if he'll swear allegiance to them. Then they'll give him an army, and he'll rule Tatooine on their behalf. He refuses, but they give him the Rancor anyway, and recommend Krrsantan's services to him.
This season otherwise follows the same trajectory, with Boba forming his small army consisting of Fennec, Cobb, Krrsantan, Greef, Cara (because we don't do cancel culture) and his Gamorrean guards. He also brings in Cobb's townsfolk, and the tribe of Tuskens now allied to them.
Final battle ensues against the Pykes, who ultimately seem to win due to having heavy air support-- but who are then beaten when Bo Katan and her buddies show up on that Imperial ship they took from Moff Gideon (and the smaller one they stole earlier, too, I guess).
At the very end, we see the remaining Pykes making a deal with Werner Herzog's character, basically forming the Pyke/Imperial anti-Fett alliance. So there we have the next season.
...which then starts with Moff Gideon being broken out of jail just before he's set to be sentenced. He's obviously eager for revenge, and he still has a few clandestine special weaons projects going on.
Meanwhile, Boba has taken Grogu on a journey to complete that trial the ultra-trad Mandos suggested, so he can get them ob board, too. Because he's not stupid, and he knows his enemies have ganged up and are preparing for a re-match.
This all got a bit long. But, yeah, obviously I think it'd be a great idea to make a series like that instead of what we actually got.
