Thank you for your comment, I'm really happy to see you enjoyed our game!
As for the WebGL builds working on mobile, it was more a happy accident more than anything, we were kind of shocked to see that it worked rather well on phones (I personally tried with my Android device and everything was working well enough, and iOS didn't seem to have working audio out of the box). We do use a custom-made template for our games, that isn't anything special actually, it just strips out some things off the default Unity WebGL template (funnily enough, I forgot to remove the check for phones that says they're not supported, despite the game still loading in the background).
If you want to, give our WebGL template a chance, it is open source, you can get it here, and let me know if by any chance it helps. Other than this, we had a rather default WebGL build config, with the recommended compression method for the jam.