The Wonder Mega Collection has little chance of being included in the Genesis Mini 2, but you know what I would happily accept as an alternative? Wonder Dog. It was a Core game, not too dissimilar from Chuck Rock, but more fun to play. I would take that, definitely.
I'm a bit confused why they went with Wondermega Collection specifically and not, say, the two Game no Kanzume (Sega Games Can) releases but I guess it'd be odd to have the Phantasy Star II text adventures but not the game they're derived from on the same unit.