Wait, can you point me in the direction of a guide where I can do game-sharing and play games online simultaneously with my partner without loging in as the other person? I'm failing to find that method. I see YouTube videos of people playing one copy of Smash Ult online with two units, but it has the account flip I said I was uncomfortable with, where as on Xbox my SO and I and never touch each other's account while enjoying all of my games. That was my primary hangup of what you quoted rather than being able to play a single copy online together being possible, however minor that might sound.
Let's call your account A and the other person's account B.
And your Switch is Switch 1 and the other person's Switch is Switch 2.
If you want to play online, the account used must have NSO.
To play on both Switch 1 and 2 simultaneously using one copy of the game purchased digitally on account A.
Set account A's primary Switch to Switch 2. This means that any account on Switch 2 can play games purchased on account A without a check.
For Switch 2, use any account other than Account A to play games purchased on Account A.
For Switch 1, you will now need internet connection and logged in as account A to play games purchased on account A on Switch 1.
Also there is a verification check every 3-4 hours, so you'll need internet connection for those checks.
To play online at the same time, both account A and B will need to subscribe to NSO. Use account B to play the game on Switch 2, while you play on Switch 1 logged in as account A.