What contributes towards completion percentage of area in Borderlands 3?

While looking on map of each location of Borderlands 3, player can see location completion percentage. Most likely, missions and crew challenges are among the things that contribute to this percentage. I'm not sure about ECHO records and Eridian writings though.

So I would like to have confirmed list of activities that are required to get 100% completion on location. E.g. there is location called Sandblast Scar, which is mostly needed for plot reasons, and does not feature any crew challenges or side quests. Yet after finishing main story, I still have only 76% completion in this area. Revealing area (making it blue instead of grey) does not contribute to completion for sure - I've checked that.

So, does anyone know what is full list of things I need to do in each location?

Just found out that while on the map screen, you can use DPad to go to challenge and then press left analog stick to see everything you’re missing.

Apparently Red Chests count.