I really think Genshin is awful on mobile. Even with a high end phone I had extremely bad performance. I haven't played Honkai so can't say anything about that.

To be fair I wouldn't recommend Genshin at all, I've been playing since launch and there's a lot of FOMO, so just by starting now you already missed many things that will never return (like weapons, events, etc).

I really liked the Nier Reincarnation game and played full f2p. The story telling and the soundtrack is beautiful. The game will be closing in the next months though, which is really sad. :(