Great questions!
Short answer, there is no good research into salt loving
mushroom. There is, however, great research into the salinity protection provided by non-mushroom-forming arbuscular mycorrhizal fungi. You can read about it
here.
I would encourage cultivating indigenous AM fungi and inoculating your plants with them to increase their resilience.
Several years ago I wrote
this article on fungal and the plastics problem. I also made
this video on how I trained Oysters to break down cigarette butts. In my book, I go into the topic a little further, but not much as there is not much more to say. It does seem like they hold great potential for addressing this major problem, but not a lot of people are looking into it.
We need to focus on non-mushroom forming fungi more, in regards to the plastics problem. Im guessing that the heavy hitter will be a soil fungus or endophytes, or (more likely) a successional guild of fungi and other microbes.
Peter