Wanted to separate this post from my previous ones, but initial impressions are surprisingly good. It's too fucking late after all the installing and tinkering to mess with in-game settings and whatnot, but I was getting 60FPS with dips in crowded areas and during combat while using lots of skills and effects, running fullscreen at 1280x800 with the generic "medium" preset. Regardless if that sounds bad, it's night and day better over running on my Samsung Galaxy S21 phone (duh). The Deck's screen really pops and Genshin looks gorgeous on there. After the controller workaround, it plays great as well. Loading is slower than my SSD on my PC (duh) as well as my regular HDD on my PC, but faster again than the phone. I'm using a Samsung EVO Select 512 card which was one of the higher rated ones for Deck. Everything including the Windows OS is running from the card, my internal drive is not being touched for the Windows boot.
I should have given in, but I would also recommend you use a physical keyboard either through the USB port or via bluetooth. The Win10 OS onscreen keyboard sucks major donkey dicks and made everything so much more difficult, along with trying to use the touchscreen to interact with tiny Windows buttons and menus.
Tomorrow I'll piss around with the game settings and see if I can get a nice smooth 60 without dips while still looking good. I could get a bit of performance leeway just by setting the resolution to 720p instead of 1280x800 which is apparently the native Deck resolution.
I took a pic just for proof that I got it working, but it's hardly indicative of the quality when you're playing the game.
It doesn't seem like it would, but just getting all of this configured and set up wore me the fuck out, so I'm done for tonight. Despite my grumblings though, I am very pleased so far and had quite a bit of fun getting things to work, but that's a personal thing of mine.