I'll echo comments about DiveVolk housing. They work pretty well for movies and music. I load up the Netflix, Hulu, Disney+ and Amazon Prime apps with movies and music.
The sound resonates pretty well especially on CCR although I can hear movies perfectly well on OC with thick hood. I use mine for cave diving a lot.
These are a couple quick audio hacks to increase volume on iPhones.
Go into Settings > Music > EQ > Set to "Late Night"
Go into Settings > Sound and Haptics > Headphone Safety > Make sure "Reduce loud sounds" is checked off.
The vendor says it's waterproof to ~260ft but I have heard of some people cracking their screens at ~200ft. I usually leave mine on my 20' or 70' deco bottle although I have taken it to 100-130ft without issues.