The feature is often not very well advertised, a pair of bt nc headphone I am looking at seem to not list it prominently despite being, imo, a pretty important feature. Searching by letter might not get you any accurate idea of what does and does not support multipoint.

Depends how much you want to spend. I wouldn't start the search with Amazon, take a gander at Head-fi.org forums.
Almost all proper headphones should support it, but it's worth verifying before purchase.
So you're better off shortlisting headphones you like, then narrowing by multipoint support, rather than only buying based on multipoint.

I use Sennheiser BT-4.50, and they support multipoint. (Frequently available on their outlet store for good prices). I'm almost certain any of the recent Sony XM range will too.

Just as an fyi, If you're looking for fully wireless earbuds they're even harder to find with multipoint BT. This is due to the fact that they're already using it to connect to both the other bud and to the device, and at least at the time the bluetooth boards that were in production were pretty much only supporting 2 simultaneous connections. I believe more have been coming out, but when I checked a couple years ago Jabra was one of the few companies making them. Elite 75ts were what I got at the time. I really liked them, but a trip through the washing/drying machines took them out of service and I replaced them with something without the capability as I no longer needed it.