Moving to my own Switch 2, transfer question..

I've been playing ACNH on my boyfriends old Switch. I restarted an island under my own profile so it is linked to my Nintendo ID but I've just bought myself a Switch 2.

I have a couple of questions now:

Can I log my boyfriends account into this new Switch and download the game and then transfer my island across?

If so, can he do the upgrade to the Switch 2 version and I can play this?

Or do I need to buy the game myself and then transfer?

Google is being unclear.

TIA!