Selective overlay? Secondary folder for same emulator?

I don't know if this is a request, bug, or not yet implemented feature. On some emulators, there is a small overlay at the bottom of the screen to do various options (Save/Load state, make full screen, apply filters, etc.). simply move your mouse and the options appear. On others, this feature is missing. Is there a setting I am missing? is it a bug? or a partially implemented feature? Having this would be so helpful to users (especially is a back button was added as well 'request'). I've noticed that a few websites (such as webRcade) have this feature on all the emulators, so not sure if it is a retroarch core thing or emulatorjs setting.

Second, I know this is two things, but what is the possibility of adding your own emulator folder and option (Not core). Meaning, say I have pce-cd and pce, currently I have to put them all in the pce folder to scan, which works as they use the same emulator.

Desired Behavior

Onscreen interface during gameplay available for all emulators. Add additional custom folder/config/art for existing emulator.

Current Behavior

Onscreen interface only shows up on some emulators. Scan pcecd roms is not shown or available.

Alternatives Considered

Don't know where the overlay feature would be found

For the additional rom type, I tried to add pcecd info/directories in all the appropriate places, and whilst the pcecd directory does show up, the scan option does not. (Don't really care about this one, but it would be nice)

linuxserver / docker-emulatorjs