Soldered a battery connector to my esp32-c5 board today with a customized case that I modified with battery clips. The seeed has a built-in GPIO connection and voltage divider for reading the level. Had to peek at arduino sources to figure out the right attenuation level, seems to be working from esp-hal in rust. I want to show the battery level on the web pages and do a safe shutdown before the battery gets too depleted.
Still prototyping; I want to add a bigger antenna, SD card adapter and a GPS module. Placement is tricky!