Considering Diablo III was available on Nintendo Switch 1, it's not exactly a huge surprise to hear Blizzard is seemingly working on a Switch 2 edition of Diablo IV. Nothing official has been confirmed as of yet, but a new rating somewhat spoils the surprise.
The Taiwanese rating board previously had a public entry for a Switch 2 edition of the Lord of Hatred expansion for Diablo IV, which all but confirms that the full game (and likely Vessel of Hatred) will soon be coming to Nintendo's hybrid successor too.
As noticed by Nintendo Everything, the rating went up in April but was only recently spotted and has since been taken down. That being said, the publication managed to snap an image which very clearly displays Diablo IV: Lord of Hatred rated for Switch 2.
Again, Blizzard has not announced anything official on the matter but BlizzCon will be taking place in less than three months, so perhaps we'll get a firm answer on this front sometime early this autumn.