To give you an idea, here’s the checklist of the game’s general progression. You can check the list of resources you have by opening the map and holding L2 until it zooms outs to reveal your resources list and general progression.
22 Story Missions
8 Side Missions
30 outposts (actual outposts are only a handful; this includes scavenging them and liberating them in higher difficulties)
10 Treasure Hunts
21 Expeditions (includes repeating them in higher difficulties)
5 Specialists
8 Guns for Hire
30 Perks (doesn’t count the stackable perks that you can purchase several times)
105 Challenges
9 Photographs (collectible)
10 Music Players (collectible)
101 Locations Looted

Note: For locations looted progression, each location is marked with a resource icon. When you visit a location, it will display the number of that resource scattered in its immediate vicinity. Find all of them and the location will be marked with a check in the map. To make it easier to find these resources, bring Timber. (with his Pointer ability unlocked) He’ll be able to reveal all resources within the immediate vicinity, even behind walls or underground.

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