A few months ago, Nintendo said you'd be able to add a note to any of your friends on your friend list, to avoid confusion in the event that they change their profile name.
This doesn't appear to be an option on the Switch 2, nor the Nintendo Switch App.
"You can add notes for every friend too, which can help you remember who they are if they change their username. Trinen said these improvements were important to make because of things like GameChat".
https://www.polygon.com/news/553620/nintendo-switch-2-friend-codes-qr-codes
by Gavintendo