i use steam+proton to run cracked steam games on my deck quite frequently actually. just gotta add em as non-steam games and tell em to use whichever proton version
Sure is. If you want examples search Fit-Girl's (or your favorite repacker's) website for the term Goldberg. If you want to know more you can find their GitLab page pretty easy.
I don't think it's completely flawless but it seems to be pretty commonly used.