Using the latest Rocknix CFW, which I've found to have the best performance and ease of use so far. Plays up to PS1 fine, and surprised at how reasonable Dreamcast is considering this is a small & cheap device! Getting 50-60fps with Under Defeat, with some brief dips during more graphically intensive parts but the game feels smooth and playable throughout
You can get much more powerful handheld devices of course but the CubeXX is great for the price (approx. $70 - UK £50), excellent ergonomics, good Sega-style floating d-pad and that awesome 720x720 IPS screen.
Quick and rough video I just made:
https://youtu.be/M0C7ffI9CO4
Anbernic page:
https://anbernic.com/en-gb/products/rg-cubexx
