Skimmed the Github page, didn't see much mention of what you may do with it, so what are some of the things you might do with these? Put backed up ROMs on'em to use with original hardware?
Yes you can use a flasher to write any MB3 and most MBC5 games that you can use on original hardware (and accessories like the N64 transfer pak). The Japanese Crystal is the only game that ever used MB30 mapper to my knowledge, so this board can play romhacks like Pokemon Coral without issues.