Wine/Proton is not an emulator, it doesn't emulate a console nor architecture. Yuzu does emulate both an architecture (ARM on x86) and the console. It then requires dumped games and and system firmware to run, which are not freely distributable.

Wine/Proton is a community implementation of the Windows APIs for Linux, it uses no Microsoft code nor needs any. It runs binaries that Valve already has permission to distribute (the games).

yes, but their interest is in emulating software distributed by steam

other games are only as much of interest as it might be games which could end up on steam or games which show some issue with the emulation which could be used to improve proton

there is also the thing that proton or wine just barely count as emulation, they are a bit of emulation but mostly just providing compatible OS interfaces adaption (through Yuzu might but be that much different given how "mainstream" (but old) the switch hardware is)

I wouldn't say so. Valve's business is selling PC games.

Wine is not an emulator, and has nothing to do with projects as Yuzu, Dolphin, PCSX2 and others.

through given how mainstream the switch hardware is you could argue that Yuzu isn't that different to WINE as you don't need to emulate anything but just provide compatible OS interfaces like WINE.

(if running out on ARM, there is still ARM to x86 emulation but that is just generic ARM to x86 emulation which has not that much to do with Yuzo per se)

WINE's name is an acronym for literally "Wine is not an emulator"

Lolol