Sorry only just saw this.
With regards to pro/supination, I don't have either majorly (one, I cant remember which to a very small degree), I do have a slightly sunken arch however.
I've fixed my cadence as I used to run with very long strides, to now have shorter strides with my foot landing below isntead of ahead of me. I've fully taken off 8 weeks as the longest period of no running time. Trainers are new and fitted by a podiatrist. Saw positive improvments for the period of Sept - Dec 2019 as I built up from about 30 secs of running but since then nothing, even with trying the same strategy. I've always done it progressively, done almost exactly as you said. Starting off with static movements and weighted physio, into plyrometric movements and then running drills and then running (using a running plan of I think 1 min run, 4 min walk and build up each week).
Havent done any road running for ages, its always been on grass/mud so as to try and stop there being so much stress going through my shins.