I've thought about this specifically with Genshin because I am a huge Genshin Impact fan lol. I think it really depends on which nation has to do the Sburb session, and there are already a lot of characters so I've just broken it down nation by nation instead of character by character.

Mondstadt: They would be able to finish the game, but they'd have a lot of curveballs just like the Alpha kids had. I definitely think they'd have to Scratch their session and have a complete do-over at some point just because of the many curveballs being thrown their way. They'd all have pretty "mid" Classpects too which would make it a little harder on them to actually get things done but I think at the end of the day they'd come together to do it.

Liyue: They would speedrun this entire joint, there's no doubt in my mind that Ningguang would do everything in her power to get to the end of it as soon as possible and with everything intact. She'd be the de facto leader, and I just can't see her being outsmarted in any capacity by the big bad of their session, so it'd be a straight shot to the end. I also think they'd have pretty weak Classpects so it'd make doing this more difficult, but they have had way worse odds before.

Inazuma: They're not winning without someone else coming in to sort of help them along. I think Ei would be too OP like she'd have an incredibly busted Classpect compared to everyone else, so they'd all have to rely on her or something. I can also see a lot of them missing steps and not really getting parts of their session done that would result in it being doomed in some way, which is why they'd have to either get someone to help or intervene. There would be a LOT of dead Inazuman's by the end of it as well, so they'd be playing on just the max difficulty. Their only saving grace would be having a lot of good Classpects on their side and having characters who really mastered their Aspect during the game.

Sumeru: They would not win, full stop, I love the Sumeru cast but they'd be too busy arguing and fighting to like get it together in the end lol. There's just too much tension in the group that I can see them splintering off and trying different strategies. None of them would want a leader at all, or they'd all have different ideas of who should BE the leader. It would be solely up to Nahida to get them out of this alive, and if something happens to her I definitely think they're just cooked. And it is very easy for something to happen to Nahida T_T

Fontaine: They would be playing this game with blinders on, it'd be similar to the Mondstadt run but they'd have a lot of mysteries to solve to get to the end of this which would require teamwork and stuff. I can see them working together for this though because its for Fontaine and they'd want to save Fontaine by any means necessary. Furina would be having a major anxiety attack the whole time though, I cannot imagine her Godtiering and realizing that means she's like a "REAL" Archon now lmao.

Natlan: They're playing on Max difficulty and someone put something incredibly fucking horrifying into a sprite meaning each day would be a new doomsday after next. They'd have weak Classpects but I think they'd get through it because people from Natlan are just built different. There would be a lot terrible things happening in their session that seem like pure bad luck meant to tip the odds against them even more. Mavuika's got that, though. Like they're genuinely just built different so they'd be able to do it like it was nothing.

Nod Krai hasn't come out yet and neither has Scezhnaya so I can't say how those nations would work in a Sburb session.