I have to send in my Deck for an RMA. As I had to reimage it anyways I decided to play around with OpenSUSE Tumbleweed. It took some small trial and error, but by booting into the Gnome live image I could enable the on screen keyboard in the accessibility settings and thus complete the install of Tumbleweed without any additional problems.
I was especially surprised to find that Gnome would turn the screen around correctly by itself. With KDE Plasma I had to set the correct screen orientation myself. And unfortunately Plasma also did not come with any on screen keyboard so it was effectively unusable.
But if you like Gnome you can put it onto your Deck without any additional hardware besides the SD card or USB stick. From a first look everything was working like it was supposed to.
I know what I will be doing as soon as I get my Deck back.
i might be wrong, but setting up the steam client as an option in whatever display manager (‘login screen’) one uses would likely work. i’ve done that with renoise the music tracker.