In my experience, streaming games with GloSSI through Steam Link has really bad lag issues. Just enough that I wouldn't want to play it.

You can add games to Steam, but there are limits. Anything that runs at admin-level, like Genshin Impact or I'm guessing most Riot games, requires Steam running at admin-level for it to work. And Xbox app games just don't work, because the Xbox app is somehow worse than buying games on CD in the 90's.