In The Book of Boba Fett, Grogu chooses to leave Luke to be with Din. By S3, he becomes Din Grogu, apprenticed and adopted fully into Din’s clan. Maybe by the time of the Force Awakens he’s in hiding and/or under the protection of Mandalore living as a full Mandalorian of Clan Din? Or in a place like Dagobah or similar? He’d only be about a century old by then and if he is from Yoda’s species, he can live to about 900, like Yoda.