Seeking Boroscope capable of focal lengths from 24 to 48 inches
Hmm.  Perhaps I asked for help too soon?
After more online searching, I found an Oiiwak Endoscope (https://smile.amazon.com/gp/product/B08L65982N/ref=ask_ql_qh_dp_hza) that claims 5cm to infinity for focal distance.  We'll see if that's a legit capability or just a marketing claim.  Anyway, I'm going to try it out.
(The product info also states that it can feed video live to a PC via USB, so I should be able to point Skype etc. to it as my video source for video calls.)
If anyone has any advice, or comments, though they would be welcome/appreciated.