I know there have been conversations within this community about PONS, but I am not sure how many of our members have tried it. I thought you might appreciate this information (and the many comments following the article) on PONS -- https://multiplesclerosis.net/living-with-ms/portable-neuromodulation-stimulator. And here's another discussion from our forums -- https://multiplesclerosis.net/forums/pons. One of the comments is allegedly from one of the physios on one of the clinical trials, so you might find that comment especially interesting.
I do hope any members with personal experience will chime in here. And, should you choose to pursue PONS, I would love for you to share your experiences here.