I am currently looking into that as well. Please keep me posted if you find a convincing solution.
I started this thread a few days ago: Waterproof hearing aid case
Looks like one of the sources I name has gone silent. Their website still works – somewhat, but no way to contact them, their Twitter account does not exist any more and the last entry on Facebook is from March 2024. But maybe I’m wrong.
Apart from water parks, there are simply situations where you need a safe, waterproof, crush-proof place for the aids. And these situations are not always foreseeable, at least not in my life.