I have a Don Hume thumb-break belt-slide leather holster for the USP 9/.40 full-size that will also fit the .45f, however, the thumb snap will not fasten unless you carry cocked & locked. It will not carry my .40 compact.
My Safariland 6240 duty holster fits my USP .45f, Beretta 92FS, and Sig P226, although the tension screw must be adjusted.
My Galco thumb-break belt-slide leather holster for a the Glock 17/22 fits my P226 well enough for carry.
I have a Bianchi M12 military flap holster that fits just about any 4"-5" barreled auto including S&W 3rd-gens, Berettas, Sigs, 1911s, and Glocks, but will not work with the USP as the trigger guard is too large. The matching magazine pouch will fit everything as well except for my USP .45f magazines. Note that the plastic divider can be removed to accomodate 1911, Glock or USP 9/.40 mags.