Won't work on GoG, Epic games, Xbox app, Cloud streaming services, emulators outside of steam, nor android. I recognize that I could add most of my games to steam with the "add non-steam game to library" function, but I prefer having my libraries seperate (idk why, I just do. Also, a handful of games I have tried do not play nice with this feature). I also use Xbox remote play and PS2 emulators often, it isn't going to work with those. Ideally, it could be detected as a standard controller when you aren't in Steam, but they didn't add that functionality.
This is definitely a me issue, but that doesn't change the fact that it doesn't meet my needs.