The Splatoon website has confirmed a couple of details regarding save data handling in Splatoon 3, as well as provided an incentive to boot the original up again.

After Splatoon 2 saves infamously could not be backed up to the cloud backup provided in Nintendo Switch Online, Splatoon 3 will support a combination of cloud backup and server-side progression. The single player data will be eligible for the backup, while multiplayer data will be tied to the applicable Nintendo account and stored server-side. According to the website, this includes "player level, ranks, items, and gear".

If a Splatoon 2 save is present on the same Switch, players will receive bonuses as well including a "Gold Sheldon Ticket" which can be used to unlock any weapon in the game regardless of your level, instant access to the Anarchy Battle mode, a raised rank rather than spawning at level 1, and matchmaking against players with similar skill levels.