Hello from a fellow Windows mISV! I'd like to say that there are only two of us remaining, but RSDN forum "Shareware and business" is still alive and kicking.
There are quite a few small ISVs out there. From the top of my head and in areas related to my own - Arq backup, SoftPerfect, Syncovery. I don't think Macrium and Glasswire are terribly big either. Ditto for 2BrightSparks. HexRays. Boatload of smaller shops in the 3D tools/plugins domain. Lots and lots of examples, they are just hard to notice because they look and feel bigger than they actually are.