The page https://github.com/libretro/beetle-psx-libretro indicates that beetle-psx can be used without RetroArch. Is there an Ubuntu PPA with this already in it? If not how should I go about compiling and configuring it standalone?
There are other libretro frontends, though I’m not sure how many support hardware-accelerated cores. If you’re okay with software-rendered, most any of them should work, in theory (assuming they support things like loading BIOS images, etc.). Check out Alcaro’s minir, I know BizHawk can load libretro cores, though I’m not sure if this one is in the mix or not, Kodi’s RetroPlayer may work, too, etc.