Did you get asked your password before? Not that you're confusing the password demand for your account or the Nintendo Network ID (NNID, which will pop up every single time you want to access to the eShop) with one for the Nintendo Online?
I was asked to link a Nintendo account, used my facebook that had saved the account and was able to log. Then it asked for a sub code with 4x4 code.
duduspace11 "Well, since we are estimating costs, Pokemon Red/Blue did cost Nintendo about $50m to make back in 1996"
Mr Puggsly: "Hehe, I said good profit. You said big profit. Frankly, not losing money is what I meant by good. Don't get hung up on semantics"
Azzanation: "PS5 wouldn't sold out at launch without scalpers."