Can you put SNES roms on a Super Mario Bros Game & Watch?
This question was downvoted mostly because we do not help with modding, and that is very probably against the TOS of that collectible.
My personal guess? Well you can't usually use the exact same emulator for NES and SNES games. Its good to remember that the Super NES was not built as an extension or buildup to the original NES, but was the following console. So it's probably not the same architecture.
So by taking that into consideration, it is improbable that just because it can run NES game it can also run SNES games.
The G&W collectible was made to run NES and G&W games, so that's probably why it can run other NES games (the NES/SNES classic had the same loophole, where its a basic emulator inside, so it could run any game from the same generation if you dumped the ROM on its memory). But it probably has just enough firepower to run NES, and wont be able to run things from a more advanced system like the SNES.