Most notably, around the 40 second mark, Favreau states that Grogu spent "many years" with Mando before the climax of Season 2... And then heavily implies that Grogu spent 2 years training with Luke before he was returned to Mando during The Book of Boba Fett.
I do find this a bit odd, given that virtually nothing on-screen indicates that kind of time-lapse(especially when it comes to Grogu's Jedi training)... But here we are. /shrug
Granted, it has been established that time works differently in places that are very strong with the Force(like Dagobah and Mortis)... So perhaps that was also the case on whatever world Luke took Grogu to? Dunno.
"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."
The biggest sign of time passing is actually Nevarro. The planet changes quite a bit every time we see it after Season 1.
However, I'm pretty sure there's also a Dave Filoni quote out there where he says that he doesn't think Mando has quite reached 10ABY, so we've got conflicting sources. Either a couple years have passed, or not quite one year. I'm waiting for something in-universe to actually confirm the timeline, rather than relying on creatives out-of-universe. That just tends to be the better approach with the way Disney canon has been going.