Highly recommend just going ahead and installing EmuDeck. I'd been putting it off, since I could run most things fine as it was, but they've really optimized the shit out of everything for Deck. For example, I could barely get the framerate into the teens in Pokemon Legends Arceus, it now runs fullspeed at 30fps (which could also be Yuzu optimization, dunno, haven't tried in a while). Also, for some weird reason, DS games weren't running well at all in the Steam release of Retroarch - in EmuDeck, I can uprez the heck out of the games (Dragon Quest IX is 5x original resolution and runs fantastic instead of a slideshow).
There are some hitches I'll have to work out - my arcade games no longer launch, but those were always weird anyway, and maybe this EmuDeck setup doesn't have the rom pack I have or whatever. Some of my saves from Steam Retroarch don't seem compatible, either, but oh well, I wasn't in progress in any games currently, so I'll just stick with EmuDeck for now.
It's also nice because instead of having 18,498 games in my Steam library list (that's a lot of roms, lol, I'm currently scraping art and stuff in Emulation Station which is where I got that number), I just have a few emulators and Emulation Station, and that's it. Still very navigable.
EDIT: Easy fix for the arcade games - I just had to change the default emulator to MAME 2003 Plus, everything works fine now just as before. Yay!