Salt water is even good at home, you can buy sea salt by the pound, just steer clear of hot water.. keep to warm.
There’s a very well researched book on PPP written by a lady in the Netherlands but translated into English.. it’s the best Pso book I’ve read yet and I’ve read quite a few. How to Treat Palmoplantar Pustulosis Naturally by Asa Karrman, that gets great reviews. I think she has a Facebook page, too.

Salt water will definitely loosen up scales and assist with skin feeling fresh

Salt water is VERY good for your skin, but if you’re broken out it could sting at first. Idk about the insoles…