@jdock64
Well, if I look here
https://wiki.recalbox.com/en/emulators/consoles/playstation-1/duckstation
under "Features" it seems that Duckstation doesn't support a Rumble-Funktion in Recalbox.

If I look here
https://wiki.recalbox.com/en/emulators/consoles/playstation-1/libretro-mednafen_psx
here
https://wiki.recalbox.com/en/emulators/consoles/playstation-1/libretro-mednafen_psx_hw
and here
https://wiki.recalbox.com/en/emulators/consoles/playstation-1/libretro-pcsx-rearmed
it looks like these are the only Sony PSX-Emulators that are offering a Rumble-Funktion in Recalbox.