What do these buttons mean in a Pulowski Preservation shelter?

On the inside, Pulowski Preservation shelters are equiped like this:

These 6 buttons don't have any actual ingame use but they could have meant something in the game history, or maybe an abandoned feature from the game devs.

Is there any clues about what they mean?

Solution 1:

We don't really know from in-game materials, so we are forced to speculate. Let's look at each button, left-to-right, top-to-bottom:

1. Oxygen?

   That looks a lot like the O2 symbol for oxygen. Nukapedia's Pulowski Preservation Shelter page notes that

The shelters contain face masks and a fan, suggesting they had some form of ventilation.

I expect that pressing that button would activate the face mask and fan.

2. Close Door

If you're inside the shelter, then the door moves to the left when closing, and to the right when opening. This can be seen in this screenshot with the sliding door partially visible, taken from Nukapedia:

So it seems pretty clear that that would control the door.

3. Suction

The shelters are equipped with a suction hose, probably for disposing of waste. In other words, it's the toilet. As noted on the Nukapedia page, Bryan Wilks mentions the hose during the Fallout 3 quest Those!

While standing in the shelter, Bryan Wilks might ask "What's this funny suction hose for?" The answer is unknown, but logical speculation suggests it's used to dispose of biological waste.

4. Open Door

As in 2, but reversed.

5. Unknown

I think that looks like an inverted bell. Normally, a bell like this would correspond to some kind of alarm, such as in an elevator. It could have a similar function the the elevator bell, to indicate to the outside world that the occupant is trapped. Maybe it's supposed to call Pulowski.

It could also have something to do with a Geiger counter, and detecting if it is safe to go outside. After entering, the booth states

Wait for radiation to clear. Enjoy your stay.

There would need to be some way to determine if the radiation had cleared, so I would hope one of those controls corresponds to a Geiger counter, and this seems like the most likely one.

I could also see that image being interpreted as a falling bomb, with fins on the upper end. This might be more consistent with the Geiger counter interpretation.

6. Shower?

That looks an awful lot like a showerhead.

Considering the radiation theme of Fallout, and the specific purpose of the shelter, it seems reasonable to conclude that this is a decontamination shower, possibly for use immediately after entering the shelter.

Conclusion

There are some other possible functions. Maybe one of those controls a light. Maybe six is actually the suction, rather than a showerhead. I think we can be pretty confident in the open and close door buttons, at the least.