Feel free to give it a try and report back if it works (note: according to the flathub page it's not available for aarch64, only x86_64 is listed).
ssh in and run "flatpak install flathub net.retrodeck.retrodeck", then try to start it directly from the flatpak addon.
so long,
Hias
You're completely right, I'll try it with Pegasus instead:
Install Pegasus on Linux | Flathub
Cross platform, customizable graphical frontend for launching emulators
flathub.org