I don't particularly care for Skaar. I've read only a little bit that had him in it but he never struck me as a particularly memorable or interesting character and I don't really wish for him to be in the MCU. I think if you're gonna use that character the best thing you could do with him would probably be to make a movie-length Frank Frazetta artpiece come to life on Gamma-Steroids with Skaar surviving wastelands filled with giant monsters like the wastes of a more comic-accurate part of Sakaar or the Savage Lands or something. But I don't see how you'd make something like that and fit it into the larger MCU, which makes it unlikely they'd want to do that imo.
As for any other Hulks they might choose to introduce at some point, I hope they only do it if they have a good reason for them in the plot. If they do have others I hope they are different enough.
If they ever do Red Hulk I'd hope they 1. Let him keep the mustache to look more visually distinct from Bruce. 2. Give him military weaponry. A Hulk that can use special big guns is more distinct than another one that just smashes stuff. 3. Really lean into the general's body being old and in decline when not in Hulk form. Having him as an old man that has to walk with a cane only to become physically superhuman as Red Hulk would make an interesting dynamic.
If Betty ever becomes one I hope she's (Red) Harpy. The design and powerset are actually interesting as opposed to Red She-Hulk who feels like a derivative of a derivative of a derivative.
Amadeus Cho and Rick Jones shouldn't become a Hulk. They're both way more interesting without being Hulks.
Characters where the Gamma Mutation is very different from the Hulk transformation like Leader or Doc Samson I'm fine with. Sasquatch is fine too. Non-gamma characters that happen to be vaguely Hulk-adjacent like Dorrek-Vell (Hulkling) or Xemnu are fine too.
I don't think anybody cares about the likes of Lyra or Weapon H or even more minor versions.