The big selling point of the cartridge is its compatibility with various disk, tape, and cartridge images, like D64, D81, CRT, PRG, P00, .20, .40, .60, .a0, and more. Just drop the image(s) onto a microSD card and pop the card into the BackBit. You see the file(s) on a menu, you select the one you want, and it loads and runs. No Commodore calisthenics to get the computer to recognize the image type.
As mentioned above, the BackBit cartridge works with the VIC-20 with a special adapter that fits the BackBit into the adapter. Evie has a video that explains it at