libretro/ports/tools

RetroBIOS in the Tools menu

Copy RetroBIOS.sh and the retrobios folder next to the other tools:

System	Folder	Menu
ArkOS, dArkOS	tools on the EASYROMS partition (/roms/tools)	Options, Tools
ROCKNIX, JELOS	/storage/.config/modules	Tools
AmberELEC	/storage/.config/distribution/modules	Tools

It checks the BIOS folder against the files its emulators read and installs the missing ones: downloaded with a network connection, or from a pack copied into the retrobios folder without one.

Controls: D-pad to move, A or Start to choose, B or Select to go back, X to tick a system, Y for the options, L1 and R1 to page. To quit, hold Select, then press Start: Start pressed first would also choose the line in focus.

ArkOS has Python 3.7, older than the installer needs: RetroBIOS uses the Python runtime the RetroBIOS PortMaster port downloads, so start that port once first.