Since this is a DSi-themed launcher, DS(i) cartridges should be enough. It would be kind of like putting a 3DS cartridge into a DSi...That's a possibility for launching DSi-enhanced cartridges, though it'd need a third CIA installed.
For 3DS games, APT_PrepareToDoApplicationJump(0, 0, MEDIATYPE_GAME_CARD) should work without issues. The "hard" part is reading the banner, and it's not really hard per se; it's just time consuming.