I have done my usual cheap-out in not buying an apple watch, and instead spent the same money on various halfway solutions that don't quite work.

Closest thing in I've found in Android world to Dawn Patrol is Waves Tracker:
web.wavestracker.comFree to show basic, costs $3 a month if you want to see individual waves stats. It allows you to upload FIT, TCX, or GPX files, so you can use it with various GPS devices. Has to be done on desktop version, so it's cumbersome.
For Apple world, I used an old iphone in a case inside my wetsuit ... surprised the GPS works but it does. However, dawn patrol won't work properly on the phone for some reason, designed only to be used on the watch. There's a secret setting to use it on phone at all (they said they actively discourage people to try), but it can't get GPS signal through wetsuit. So...I got another app Watersports Tracker, email myself the GPX file, upload to Waves Tracker, then view it on phone. And with all that, my attention span lasted about a half dozen sessions.