https://sidedeal.com/deals/2-pack-infinity-x1-stereo-wireless-rechargeable-700-lumens-worklights-with-blue

Two speaker/flashlights for $25, bluetooth, claimed lumens and runtime suggests there are two 18650’s inside each one. Quick search for reviews indicates they have USB-C in and USB-A out (you can use them as power banks), they look fairly solid, but that the speaker volume is not all that high. I’m gonna resist though.

Meh had some quite nice ones a few years back that I still sort of regret not getting but it would have just been more crap around the house. Edit: found them:

https://sidedeal.com/deals/libratone-zipp-zipp-2-360-wifi-mutl-room-speakers-with-airplay-2-alexa-7

The large ones (original Zipp) without Alexa seemed very decent though the micro USB charge port is ugh these days. I saw a teardown indicating four 18650 inside. People said the audio was good. I see them on fleabay now for $100+. IDR what Meh was selling them for but it was definitely less. They are indoor speakers though, not waterproof or anything like that.

It doesn’t drive as much sound as my portable guitar amp, but for a battery based speaker, does pretty well. If you buy two of them, they’ll figure out how to work together to provide surround sound, otherwise a single one will play stereo audio to fill the area.

Had it for around 6 years and it still holds a charge like the day I bought it (I usually need to charge it every couple of months).