In their image it looks like pin 5 is getting positive. I would expect it to work for a short time without a resistor then fail, but if you have a couple you could always sacrifice one with a test.
bigclivedotcom has a few button videos covering elevator and industrial illuminated buttons. I don't think he's done exactly the same as this, but I think no real standard, but they may be cloned off a brand.
Interesting videos to see what's inside the different types. Some use a dual chip back to back parallell led - so that it can light on each half wave of a.c. - or if d.c that'd be either polarity. some have resistors, some have resistors and capacitive dropper (mains rated)
I'd guess the reason for the voltage range is the different resistance included. I don't think you'll really know unless you either measure the current draw, or open it up.
Thanks! I pulled up a few roughly similar, though modular pushbutton videos. I also found an old reddit thread about some significantly nicer Allen Bradley switches, and some general reading about how these sorts of switches are supposed to be deployed, and I'm inclined to think the necessary components are part of the assembly already. I've hooked it up to 3.3v on a USB breadboard power supply, and I'm just going to let it run for an hour. If it doesn't burn/blow out, I'll feel confident enough to use it. It's never going to have more than that on it anyway.
For DIY - this is also a placeholder.