Update: Nintendo’s UK site adds more info.
Update #2: Nintendo’s UK site now has information relating to the cloud save situation.
This game does not support the Save Data Cloud functionality of Nintendo Switch Online. However, the ability to recover Animal Crossing: New Horizons save data from the server in the event of console failure, loss or theft will be available to Nintendo Switch Online members sometime in the future.
Read the full article on nintendolife.com