Nintendo has updated the usability clause for Animal Crossing: New Horizons, noting only one island is allowed per console, irrespective of the number of user accounts on the Switch console.
It was mentioned in the initial Animal Crossing: New Horizons announcement you could only have one island per account, but the updated usability clause notes that's one island per Switch console.
Noticed by GamesRadar, the clause states the following:
"Only one island can exist per Nintendo Switch console," it reads, "irrespective of the number of user accounts registered to or copies of the game used on one console.
"One Nintendo Switch and one copy of the game is required for each unique island."https://youtu.be/nCwVTCxm29c
In other words, you won't be able to build an island for each profile if you share a Switch with others in your household.