I Believe this crate with the lock on it has a picture in it and if it were to allow us to interact with it. We would have to take it to the Crossroads

The Crossroads not far from the FOB

I believe we would find our next stop here. Few things might happen! It will open up and we can enter further or it will release a new monster that will come after us at the FOB.

If the "new monster" comes for you i can only assume we have to escape and by that i believe we would have to use the helicopter on top of the FOB.
If you interact with the Helicopter it would do a radio voice and you will see Jets fly from West to East.
what they do i don't know yet! but also looking east from on top of FOB you can see a UFO past a gate.

In the FOB there are two rooms with symbols above the entrance at the door and there is a LOCKED door totally unclear of what may lurk inside that room but it might have something to do with A Dilemma. Also the gnome no one has ever seen! I see you :)

All of this is just a theory seems that nobody knows how to get the last achievement i've even reached out to KevTheDev and have not got an answer yet. :( Thanks to all and anyone who has an idea to support any of this. Like whats up with the Southern Stump Entrance with that case under it??