Are you able to open the terminal in the recalbox?
Maybe the commands below in the terminal will work
sudo add-apt-repository ppa:gregory-hainaut/pcsx2.official.ppa
sudo apt-get update
sudo apt-get install pcsx2-unstable
They work on the ubunto
I pressed f4 + alt f2 on the recalbox but did not authenticate user and password (user root pass recalboxroot)
I'm a beginner