It has.
1st finding in here: Talk about the Planes and Airports in Generation zero
and 2nd repost in here: Norrmyra Artillery Base + FOA 2
As of what function it has, your guess is as good as mine. Also, FOA2 has been changed several times with last updates and it’s unknown what eventually happens with it.
Has one potentially tried getting under it?
…huh. Never seen that before, must be a recent addition. Mysterious 
Can’t really find a way in. I wonder if the button actually activates another lid, perhaps on a timer. Or enables access through a gate/door nearby. If I am not mistaken, one of the perimeter gates are locked. But again, I’m just speculating here.
Someone got a look under it, back in May '20. Though, it could’ve changed since. Pics in this reply here: Norrmyra Artillery Base + FOA 2 (2nd pic).
Here’s something interesting i found within the February '20 update:
Two maps. Left one shows attack plan on the Airfield but it’s the right one that is interesting.
Close-up of the right one. It looks as Himfjäll and bigger island above it are connected to the main island by land.
This may indicate that at some point of the future, when bigger map is also released, they both get connected to the main island.
Here’s current map for reference.
cool, where did you find these maps?
Right, loc too. Stenbacka (Farmlands), (-304, -2372).
Found the same map on the table in the little house in boo. Look at Gysberts Post.
Not only that, the entire landscape looks slightly different
Have you take a look into the little hut in the north from Boo.
The scene inside is a little uncanny. This doen’t look like that FNIX has to do with it.
The corpses look like somehow arranged. It looks like that they where killed by a single shot.
Was it the iron church??
Thoughts ?
It looks like bigger island is smoothly part of the main island. While Himfjäll has a land bridge.
Not only that, the entire coastline is slightly different, at least one facility is missing, and some of the smaller islands are also different.
Can you locate them and show ?
Specially the facility you mentioned??
IGA is missing from the map.
Edit: Others missing are Hjortqvarns Sagverk (sawmill), instead crossroad to the Himfjäll land bridge is there and town of Lerberget is also gone.
IGA appears on the map and physically everything is there.
The others i have to check.
I was thinking maybe that new map is from the time when GZ was still in development, e.g in Beta but that is not the case.
Here’s how GZ map looked during beta:
It’s clear that bigger island is not part of the main island.
You mean the most Northern island right?
Or the little island with a collapsed bridge at Himfjall?
Yes, that one. Just compare the map i found in-game to the current map. Or better yet, travel to the loc and look it yourself. It even has roads painted on (which my screen didn’t capture that well).
