Isn't it possible to just buy one digital copy then multiple SD cards, or is that not a thing?

Won't work, it's tied to the Nintendo Network ID that's tied to the system, and the system knows if you've tried to copy data to another card and use it, so for each digital copy, you need a Network ID.
I believe this adds up to 5 copies for myself. Two main towns, two sister towns, and a test town where I test different theories of the game.
View attachment 184601
Won't work, it's tied to the Nintendo Network ID that's tied to the system, and the system knows if you've tried to copy data to another card and use it, so for each digital copy, you need a Network ID.
I believe this adds up to 5 copies for myself. Two main towns, two sister towns, and a test town where I test different theories of the game.
View attachment 184601