This was recently asked on the "Love The Navion" FB group. Statistician extraordinaire @billla compiled a spreadsheet of U.S. FAA registrations to point us in the right direction. There are, as of August 2022, 871 Navions on the FAA registry.
http://www.navioninfo.com/files/allnavions.xlsx
I personally know some of these registered airplanes on this list that don't fly, but I'd imagine that if you're taking the time to renew the registration, the vast majority of these airplanes are flying.
When Budd Davisson wrote the Gene Padgett Navion PIREP for Air Progress in 1988, there were about 1400 registered. Keep in mind that registrations back then didn't expire like they do now, so assume that some % of those 1400 didn't fly. We're still at 62% of that number, 34 years later -- and to be sure, some of that attrition is due to airplanes that didn't fly, even then, being culled from the register.
Not awful. We can do better, but not awful.