DISCLAIMER: Expressed views on this blog are my own.
I've been doing this since 2019-2020. It's been off and on before that, but I fully committed to it at that point. AM/PM is great and all but learning and getting used to the 24hr then translating in my head to PM (AM is straightforward) becomes muscle memory.
I can look at 20:00 and say 8PM very quickly. The math is straightforward: 20:00 - 12:00 = 8:00 then slap PM (save for the 12AM/PM case). Obviously you are not going to do 11:00 - 12:00 = -1:00 for AM when you can say 11:00AM = 11:00 (24hr time), but it does tell you that it is 1 hour before 12PM since 12PM is the reference hour. This technically defines AM/PM. AM is negative and pm is positive from the mid day reference point.