I've seen cropped versions of this picture from the AWESOME Star Wars Wildlife Field Guide pop up since Mando... if you read the whole thing, it does seem like the show used established (albeit non-canon) Krayt Dragon lore.
- Swimming through sand
- eating Sarlaacs
- The Pearl
- Swimming through sand
- eating Sarlaacs
- The Pearl
The design is also very similar, and we now know that the dragon in the show also had legs. I wonder if the team had a copy of this book on hand, @PhilSzostak