I'm on Steam beta so I don't know if it's a beta feature or not but, I can right click a game in Steam's standard UI and configure my Steam controller without going into big picture.
It does pop up the big picture config in a window without the button hints at the bottom but, it's better than waiting for BP's logo animation plus nav time and hassle.
This seems to work for non-Steam shortcuts in Steam as well.
[–] Kylan ago
Thanks for the tip. I'll have to try it. Would make a big difference