Out of the box, don't even bother
While I have a Steam Controller (OG) myself, it truly feels like an early prototype compared to controls on the Steam Deck. As a PC gamer who plays on mouse and keyboard, I found its utility to be very limited given that I wasn't interested in using it for the kind of games it was designed for. It really wasn't versatile at all, but it has a cult following by people who invested some time into learning how to truly benefit from it.
I am really looking forward to the successor, because I absolutely love Steam Deck's controls. The touchpads are amazing for camera controls compared to thumbsticks, but at the same time, I get the tactile D-pad and everything else I need for other types of games.