The Wii Mini can't be trimmed as far down as a normal Wii and they don't have GameCube ports so you cant play Gamecube games. You should just use a trimmed 4 layer Wii.
He used a retron 3 for the portable sense their isn’t any trim for the original snes. You could alternatively use a snes jr but those are pricy. But you can play any snes game with them so it depends on what you want for your project
I mean I can understand why they didn't trim it. An untrimmed board cost way less to manufacture. But for size, and battery power they should have trimmed