The Sig holster is very similar to the BlackHawk SERPA except for the shape of the button that you push with your finger. If you check P250Sig.com, there's a link about the available P250 holsters including: Ankle holsters:
-DeSantis Apache ankle rigs will fit the Sub-Compact models
-Uncle Mike's nylon ankle holsters are available to fit all of the Compact and Sub-Compact models
Duty holsters:
-Don Hume H738 and COP I will fit the Compact models
-Safariland 6360 will fit Compact or Full-Size models
-Safariland 6280 will fit the Compact models
Concealment holsters:
-BlackHawk SERPA CQC holsters will fit the Compact models but in right-hand only. It will supposedly only fit the first-generation frames as of right now.
-CrossBreed Super-Tuck Deluxe Inside Waistband holster will fit the Compact and Full-Size frames. They are a somewhat-custom holster maker. It has a leather and kydex construction. (Sold through crossbreedholsters.com)
-DeSantis FFDO (Federal Flight Deck Officers) belt holster will fit the Compact and Sub-Compact models
-DeSantis SkyCop crossdraw belt holster will fit the Compact models
-DeSantis Speed Scabbard 3-slot belt holster will fit the Compact and Sub-Compact models
-DeSantis Pro Stealth ambidexterous - Nylon IWB holster - part # N87BJ88Z0 (package will say SPRINGFIELD XD9, but confirmed to fit P250 by DeSantis)
-Desantis Pro Stealth ambidexterous - Nylon IWB holster - part # N87BJLAZ0 (package says fits most large frame autos, and I believe this is the same as the above model, but am including it just for reference purposes, I have personally tested it on the P250 and it fits with the holster extending past the slide by approx 1/2 inch)
-DeSantis Tuck This II - Nylon Tuckable IWB - part # M24B88Z0 (package will say SPRINGFIELD XD9, but confirmed to fit the P250 by DeSantis) ** also available in Left Hand
-DeSantis Thumb Break Scabbard 3-slot belt holster will fit the Compact and Sub-Compact models
-DeSantis Viper paddle holster will fit the Sub-Compact models
-Don Hume DAH, H710, H721, and JIT Slide belt holsters will fit the Compact models
-Don Hume H715 Inside-The-Waistband holsters will fit the Compact models
-Galco Concealable Belt Holster will fit the Compact models
-Galco COP 2-Slot holster will fit the Compact models
-Galco Jak Slide holster will fit the Compact models
-Galco SSS Side Snap Scabbard holster will fit the Compact models
-Galco Yaqui Paddle holster and Yaqui Slide belt holster will both fit the Compact models
-Galco M5X Matrix paddle holster will fit the Compact models.
-Galco M7X Matrix snap belt loop holster will fit the Compact models.
-Galco X project (M1X) snap belt loop holster with retention strap will fit the Compact models and can be adapted to a shoulder holster with optional parts.
-Minotaur MTAC and Spartan Tuckable Inside Waistband Holsters will fit the Compact models. They are made of a leather and kydex construction. (Sold through Comp-Tac.com)
-Raven Concealment holsters say they will only fit the first-generation Compact models. They are a semi-custom manufacturer and will probably update to the new frame style soon. (Sold through revenconcealmentsystems.com)
-Safariland 567, 568, 569, 6287, 6367, and 6377 will fit the Compact models
-Safariland 6367 will fit the Full-Size models
-Sig-Sauer paddle holsters will fit the Compact and Full-Size models but in right-hand only.