I do want to warn for the case of Genshin about Mihoyo banning people as the only way to get it working is with that one Anime Game Launcher that bypasses the anti-cheat.
The game still runs in SteamOS that way, and while I do know people often say it’s not often it happens or rarely gets reported of happening, it is still a risk and I remember seeing somebody having a breakdown on r/steamdeck a few months ago because they lost a ton of progress in Star Rail after doing the same thing for it on the Steam Deck.
The safest option (what I do personally) is just using it on Windows.
I was in pretty much the same position. 2017 gaming laptop but it was having hinge issues so I finally upgraded to the Steam Deck. I have dual boot into Windows, a dock and USB hub, a keyboard, mouse, external hard drive, and monitor and even a tiny desk fan for good measure on cooling and I just primarily use Windows and then will go to SteamOS for portable gaming time to time. It has replaced the laptop well and fits a (larger sized) purse, and I have nothing else to say besides that it works pretty well for me.
Of course, it looks weird using it, but I can still be productive on the tiny screen outside using a giant monitor. It is very doable, it’s just going to take accessories and be kind of weird in general. But I’ve been at it for a year, so… it’s possible if you’re willing to set it up and find a way you want to do this!