Beetle ESP32-C6 battery power

I’ve built a student response system that mounts to desks in a classroom. Each unit sends a single signal via ESP-NOW to my computer to register a pupil’s response. My question is about the battery setup. I’ve suddenly started worrying about battery safety and want to make sure I’m using the right chemistry and protection.

At the moment each device uses a single 18650 cell (Samsung 35E, 3500 mAh). The aim is for the system to last at least half a term between charges. The firmware drops the ESP32-C6 into deep sleep when not in use, so daily power draw is tiny.

I’m unsure whether lithium-ion or lithium-polymer is the safer or more suitable option for a classroom setting, and what protection hardware I should include. Does the Beetle ESP32-C6 have a charging/discharge protection circuit? Or use a protected 18650 cell, or add a separate protection/charging board for over-charge, over-discharge and short-circuit protection?

I want to make sure the design is robust and safe before rolling it out across multiple desks, as it's in a school needs to be very safe.