Huh? You mean the Unova fighting type ones?
I'd love it if they made Keldeo not mythical any more tbh. It made sense in gen 5, but not really anymore.
I've held that opinion about mythicals for a while; that it makes sense in the gen they're introduced and at a
stretch a little while into the gen directly after; but beyond that point it shouldn't be a thing. And especially since the roster is being cut down, I think it's the perfect time to implement that.
I would also say that I think it's a little premature to think that a Pokémon would have to be thematically appropriate to the region for it to be in the game because
A) They've already stated their intention is to go with the more popular Pokémon so dexit doesn't sting as much, so being thematically appropriate unfortunately isn't their priority
B) We have no idea what form the Pokédex will take
They have said "Only Pokémon that are in the Galar Pokédex will be in the game", but what will the Galar Pokédex look like? For all we know it could contain pages for Metagross and Palkia and Hoopa, but they're exclusively Pokémon that can be transferred. You can of course argue that no game before has had transfer-only Pokémon in its regional Pokédex, but I think also the point is that that's because those games had a National Dex. There's no precedent for a game that doesn't have every Pokémon so we could expect anything from everything being available within the game to a SM-esque situation where there's postgame-exclusive Pokémon in the Pokédex to an Ultra Wormhole situation to, as I said, a scenario where there's some Pokémon only obtainable by transferring.
Until they make a statement saying that every Pokémon in Galar's Pokédex is obtainable between Sword and Shield versions without the need of transfer, I think the bets are completely open on this one. So I don't think we should really factor in things like "Groudon and Yveltal don't make a lot of sense with Galar's lore" too heavily when considering what Pokémon Game Freak will include to appease their crowd who vastly likes legendaries, and who they've previously appeased with Hoopa Rings and Ultra Wormholes.