I have done a couple pistol training courses in last year. One was conceal carry specific the other was a practical pistol shooting course. BOTH did not allow serpa style retention holsters. Fwiw. Safety being the concern. Makes sense. Under pressure of even a simple training course with a dozen folks watching I could see how it would be easy to fumble with a retention holster where you’re having to push a button to release the gun. They also touched on how poor fitting serpa holsters can and do put pressure on the trigger.
Train, train, train, train. Cannot emphasize that enough. If you think your ok or even good and haven’t taken a course I suggest you do and be prepared for a big helping of humble pie and a lot of fun! Can’t wait to do it again when it warms up!