The AceBeam Pokelit is $17 and up:

https://www.amazon.com/ACEBEAM-Pokelit-AA-Rechargeable-Flashlight/dp/B0B1Q646BK/

It has USB-C charging on its internal battery so it should be quite waterproof.

The Wurkkos FC11 is $27:

https://www.amazon.com/Wurkkos-Flashlight-1300Lumen-Waterproof-Activities/dp/B08JCM95X6/

It is rated IP67 (submersion waterproof) as long as the USB-C charging cover is in place properly.

The Streamlight Microstream USB is $33:

https://www.amazon.com/Streamlight-66604-Microstream-Black-Flashlight/dp/B077BLB1DN/

It has a USB charging port behind an o-ring so it should be more reliable than a flap. The last one I held was micro-USB, they might have been upgraded to USB-C (I can't tell from the Amazon page).

The FC11 is the largest, but it will be brighter and has a larger battery.