Blast Em. https://www.retrodev.com/blastem/
Standalone (not retro arch). Modern emulator (don’t think it’s updated anymore though). Linux support. I think it’s also available on Flathub if you want to get it via there.
Or…
Ares. https://ares-emu.net
Multi system emulator originally developed by Near (rip). Yes, it plays more systems than you are looking for, but it is simple, standalone (no retroarch/libretro), very good, Linux support, and still updated (latest version 23 Jan). Also available on Flathub if you want it there.
I suggest to try these emulators, they’re modern and they aim for cycle accuracy, rather than finding a way to keep a 15 year old emulator running.