How can I obtain a Peace Officer's Standards on Training (P.O.S.T) Certificate while on Active Duty?

There are college courses available for POST certification you can look in to, but it will be difficult, if even possible, to do while on AD.

SGT(P) Abner Lozano have you talked to legal assistance to see if your active duty status triggers Posse Commitatus, even though you are seeking a reserve officer status.

Other contributors have commented on POST certification. Reserve officers have a Diet Coke version of POST at least where I live. It is only the County Sheriffs Office. You do weekends for like 6 months and two weeks in the summer and have to redo it it every year. It is not transferable to being hired full time. They are used in jails or where ever they are needed. They want you to volunteer 48 hours a month. You have to buy all your own gear. It's enough to put you out on the street, but unless you had full time POST certification, the time doesn't count.

Montgomery County TN has a Reserve Officer program https://mcgtn.org/news/reserve-deputies-graduate

Depends on the state you want to work in. Oregon requires you be employed for training. My brother worked in Colorado where he and his son went to POST and we're then hired by department. Check with the state you want to work in.......good luck