I found some random thread about the Steam Deck that said external monitors are disabled unless you set your device to “Boot into desktop mode” so I tried that and it still didn’t work

I don’t have a steam frame, sorry, but I am typing this using an external monitor hooked up to my deck. I do not have it set to boot into desktop mode.

I bought a dock about 2 years ago that looks similar to this:

Image

and it just worked. Detected the external monitor and auto configured for it without any issues.