I needed a solution when I bought a pontoon boat in 2003, and even more so for the kayak a few years later.
The best I could find was a simple dry bag. Critical items like phone and keys went into another small dry bag inside than.
After moving close to a river there was a lot of wading while fly fishing, the dry bag worked faultlessly and could've been a flotation aid if ever necessary.
This bag has lasted years and hundreds of hours worth of fishing trips, I'm 100% sure it has a pinhole or two which makes no difference