When looking into scar tissue treatments I came across a topical treatment for scars called Scar Away. It is a Perrigo product. I think it might be the only FDA approved treatment for surface scars. It's some kind of silicone gel.
Apparently, it actually does work to reduce the size and appearance and hardness of scars on the skin. They have tubes of gel and gel sheets that you wear. I think you have to use the product twice a day for months before you see any results though.
Maybe this could help with Peyronie's Disease if we apply it to the plaque area every day for 6 months or so. If we can reduce the size of the plaque or soften it, then maybe it will help straighten the penis?
Posting this here because there doesn't seem to be a subforum for topical treatments in general.
Silicone gel (Any brand) is the only substance shown to help w surface scars as it helps the skin retain moisture. There's no thought it can penetrate beyond the skin to help w Peyronies Disease plaques.