Yep it works great. And as a matter of fact, you can set the emulator (like Yuzu) to launch at a higher resolution like 1920x1080 without any performance cost. And this way it looks extra nice when displayed on your deck, and is appropriate for when you run on the external display.

Go to the Steam Properties for the game/app, and set the resolution there. But also toggle the setting for internal and external display to ON, so it is forced. If you do not see it after selecting the resolution, just flip between the compatibility tab and back.