I don’t know if it works on SteamOS, but I use my deck in Windows very, very frequently due to using it as a main computer and I had a giant stack of years worth of code cards from the SUMO/XY era I never touched. I just used something called Camo to used my phone as a webcam and got through the stack pretty quickly.
I imagine there might be something similar for SteamOS, especially since you can use a phone as a mouse and keyboard with KDE Connection.