One of the perks of signing up with the Nintendo Switch Online service is that it gives players access to a library of NES games. These NES games are run using an emulator and as it turns out, the emulator has already been hacked which means that in theory, gamers will be able to download their own NES ROMs onto it.
The hack was discovered by a modder who goes by the name of KapuccinoHeck. According to them, apparently it is pretty easy to load up ROMs onto the emulator. This is because the ROM handles NES game files like plain .nes files, which means that manipulating these files will be easy enough.
good lord #NintendoSwitchOnline's NES games are plain .nes files GUI appears to be entirely LUA much like the S/NES Classic so people are gonna be able to go to town on this
Unfortunately according to KapuccinoHeck, this only works for Switch consoles that have already been hacked. Unfortunately hacking a Switch isn’t particularly easy and is time-consuming, meaning that this hack is more catered towards those who have already hacked their Switch, and it also serves as a proof-of-concept and points out a potential flaw in Nintendo’s system.