If that is a USP Compact in 9 or 40, the mags are the same as the P2000 mags in 9 or 40. I have bunch of mags for a P2000 in 9. Some started out life as "USP Compact" mags, but they are all the same in specs. Maybe some little minor differences in markings.
I did a thread on P2000 mags and baseplates at some point. It probably shows the markings.
If the barrel isn't over 105mm, you don't want anything to do with that. I'm not even sure that gun was produced before the law changed. Regarding that P250, it says "Barrel Length 3.9 in". If that is true then there is no way that gun would be able to legally come into Canada and be registered into the system for transfer to an individual.
On that USP Compact, it says "High cap pistol" and "THE PISTOL ONLY COMES WITH ONE 13 ROUND MAGAZINE." That cannot be correct if it is legal. 13 round mag pinned to 10 maybe. Between that and the picture with the clearly sub 105mm barrel, stay away.
P.S. - Wow! He says $430. If sellers in Canada could sell restricted USP Compacts for $800, they would be moving them like hotcakes. $430? That is just bizarre. It all seems to point to a United States gun, with U.S. barrel, U.S. hi-cap mag, situated in the U.S., and for sale at U.S. prices in U.S. dollars, and somebody probably just posted it on there not realizing that the name of the site is firearmscanada.