There are no specific duty holsters that I could find, as I don't think that anyone envisioned the gun for duty use. Safariland does list a belt mounted holster with an ALS, add the thumb switch thing and that meets my dept's requirements. I really dislike that vs. the ALS/SLS, but we already approve it for other guns.
The range master and I can approve any gun for new hires if the G17 doesn't work for them, we're trying to lay the ground work for when we do and allowing anyone to shoot the gun.
Our Admin/dics carry either the G17 of G19 they were issued or something else they bought if approved.