With the Day One update released yesterday, Nintendo has also brought the Friend Codes to the Nintendo Switch. So you have to exchange the codes again to add friends.
Nintendo had released yesterday’s Day One update of the Nintendo Switch for download and the online functions including the Nintendo eShop unlocked. However, the popular friend codes were also returned. These 12-digit codes generated for each player help find their own friends and add them to the new console on the friend list.
Furthermore, you can search locally for players, select from a list of recently hit players or link the Miitomo as well as the Super Mario Run accounts. The Friend Codes are unbound from the Nintendo Account ID. This is required, however, in order to log in online and also in the Nintendo eShop shop. So far it is not possible to import Facebook or Twitter friends.