Starting with Recalbox 10.0, the paid Pico-8 emulator can be used, but you will need to install it yourself. Here are the steps to follow:
You need to prepare two files to place in your Recalbox in order to use Pico-8. This procedure varies depending on the board.
Place the following two files in /recalbox/share/bios/pico-8 from the archive created by the emulator developer for Raspberry Pi:
pico8_64 if you are on a Pi4, Pi5 or Anbernic RG
pico8 if you are on a Pi3 or Odroidpico8.dat for everyonePlace the following 2 files in /recalbox/share/bios/pico-8 from the archive created by the emulator developer for amd64:
pico8_64pico8.datOnce you have copied the files according to your installation, simply launch any game associated with the PICO-8 emulator to use it.