Super Impulse recently released a mini TMNT Arcade Cabinet that looks very cool, but is not all that fun to play. If it were up to me, a Turtles handheld would be a pizza box that looked and functioned like a Game Boy Advance SP.
You could fit all 3 NES games on there, plus the Game Boy game (Fall of the Foot Clan), and even Turtles in Time from the SNES can be included, thanks to its 2-button control scheme.
It would be awesome if this handheld could feature multiplayer somehow, even if an old-fashioned game link cable is required. Multiplayer is something I wish these modern handhelds (from Anbernic and Powkiddy to name a few) could do, as I can’t tell you how often I’ve wanted to play Turtles or NHL ’94 with a friend.