Here are the ones I know of that are available in at least one model factory threaded...
Ruger 22/45 Steel, or LITE
Talo Ruger Mark III
Ruger SR22
Ruger Charger
Browning Buckmark Whisper.
Smith and Wesson M&P Compact
Sig Sauer Mosquito
ISSC M22
Tactical Innovations Cohort
Intratec Tec/Scorpion 22
These are the ones I know of that are threaded, BUT require an adapter
Walther PPKS 22
Walther P22
Colt 1911 22
GSG/Sig 1911 22
Smith & Wesson 422-622-2206-2213-2214
Smith & Wesson M&P Full size, and Compact
These CAN be threaded, but require machining
Beretta Neos
Beretta Bobcat
Im sure there are others.
I like the Ruger 22/45, and the Smith & Wesson 422 2213 2214. The Ruger is such a good pistol, its hard to beat it for a host. Its durable, accurate, and low cost.
The Smith & Wesson 422 series is a good choice because of the unique design. It has a steel barrel captured in an aluminum frame by a barrel nut. Unscrew the nut, replace with a threaded adapter, and you are ready to shoot. Because the barrel is low in the frame, there is plenty of clearance above the suppressor for the sights. These guns have been out of production for years now, but they show up from time to time.