By any chance, do you have a working pack of BIOS for Retrodeck? Just uninstalled Emudeck to try it and apparently it is more restrictive in terms of allowed files
I emulate it using Yuzu. Ryujinx might be an option, but I haven't tried it because it runs great on Yuzu already. If you're looking to install several emulators, give Emudeck a try. There are several guides around to get everything ready (don't rush it!).
By any chance, do you have a working pack of BIOS for Retrodeck? Just uninstalled Emudeck to try it and apparently it is more restrictive in terms of allowed files