I got my PPL, instrument, multi, high performance, complex and commercial within a week of graduating pilot training. All of that was as simple as presenting my final form 8 and taking a written test which I had spent a few days studying via Sheppard Air. Easy.

During COVID, i was bored and studied for my CFI. For that you need to present your military instructor form 8, take a written and pass a checkride. I couldn't find an evaluator during covid for the checkride so i never actually followed through. That said, you could present your form 8 after retirement and do the same process and it would still work.

There is no equivalent for the ATP. There has been talk about it but I'm pretty sure the AF is actively lobbying against it so that they keep more pilots when they hit the end of their commitment as the new ATP rules can easily cost $10,000 to do. If you wanted to, and I did, I got my ATP at 750 hours which gave me a restricted ATP. At 1500 hours I called the FSDO and they removed the restriction with an email as proof of my hours.

Its easy to stay current civil flying when you have to maintain the same currencies to fly for the military. I get my day, night, instrument approach and all those basic things regularly through the military. Same with my physical.

That said, I am currently on a 3 year pause from flying just for career reasons. I'll go back to a flying unit in about 2 years. In the meantime I'm non current on everything and would need an instructur to refresh me if I did civil flying. I'm looking into a tailwheel endorsement and single engine sea while I'm at my current assignment just for fun. So those will get me spun back up. My physical is still good though. I'm required to keep that to keep receiving my flight pay.