I did a search on the image. It turns out the original source of the image is a Reddit post by someone who bought the keyboard on eBay. It's a Sperry Univac keyboard with Hall Effect switches. Knowing that it's from Sperry Univac may give me a chance to find other images of the same keyboard to determine what terminal it came from.
Yes! I struck gold. Using the name of the manufacturer, I found this thread on Deskthority:
https://deskthority.net/viewtopic.php?t=22641which provides many more pictures of a specimen of this keyboard without a missing key.