I think that’s going to be painful.
If I try to install everything from the terminal libretro-*, some packages (such as fba and fbalpha) conflict.
I reinstall Gnome software, which has a submenu for installing add-ons, but it doesn’t work because flatpak/falthub is blocked in my country. I use a VPN, and the option submenus is no longer available.
I don’t use Snap. too many programs consuming resources just to install programs
In any case, the cores I use are outdated and cannot be installed. Sorry for the Spanish spam:
“Los siguientes paquetes tienen dependencias incumplidas:
libretro-mame : Depende: libflac14 (>= 1.5.0) pero no es instalable
E: No se pudieron corregir los problemas, usted ha retenido paquetes rotos.”
Or, they are not DB-Pure.

To activate the download, is that option in the interface? ‘show core update’
PS: I had the stable ppa activated and hadn’t noticed it; in the stable version there are about 4 cores. lol