well you just said it yourself, it would be possible because of what happened in the past, so you basically answered your own question. However, i assume you are asking if it would be possible to create a hack/exploit from this and im guessing the answer is, probably not. The reason that Cube Ninja was able to run code was because CN would crash the game, allowing for code injection, where im assuming ACNH does not do that. Another example would be the infamous twilight hack, where you could enter more than 5 characters for epona's name and because of that the game would crash and allow for code to be executed.
That all being said, IF hypothetically, it was possible too crash ACNH by doing something in game and use the QR code injection, then i guess it could be possible, however, i wouldn't hold your breath.
