Here in order to run qFlipper on a Stem Deck you will have to run couple of commands , one to disable readonly in system and second to grant access to USB port for User (YOU). Just hint: default password is “deck” and also default user is “deck”.
Disable readonly :
sudo steamos-readonly disable
To allow access for serial ports (USB):
sudo usermod -a -G uucp $USER
(note: replace “$USER ” with your user name ! mine is : “deck”)
I had couple of SteamDecks and both of them were running qFlipper app without any issues ! NOTE: with every SteamOS update you may have to redone these two steps as qFlipper probably won’t work.