If you have an Avermedia Live Gamer EXTREME 3 USB 3 device like I do, you can use ffplay and ffmpeg to run it on fedora / bazzite linux, maybe others, I'll try in on my pi5 too and report back to you if it works there as well...
The scrips runs fullscreen by default,
- press "F" to switch windowed / fullscreen
- pres "Q" to exit
Tested with a 5-way HDMI switcher and a C64 MINI, an NES mini, a PS1 mini, a SNES mini and the A500 mini...