I always thought that model was only sold to LEOs.
It can be. It isn’t imported because without some changes it doesn’t meet the criteria for legal importation. LE can get them in the US. Once they bring them into the US, they’re legal for anyone to own, so a former LE gun can legally be owned by non-LE.
The G25 is popular in countries in South America where civilians can’t own 9mm, and elsewhere where they have the same restrictions, like other Latin countries and some places in Europe.