In general this guide is too high level.

For example: what does it mean "Built-in battery support."?

- will it allow you to monitor the battery charge? - can I charge it using the micro-USB - does it have undervoltage protection? - what is its quiescent voltage? - what is its consumption in deep sleep mode?

As for the Esp32-Cam, those little camera modules are flawed, one of the pins act as a 20Mhz antenna and causes interference everywhere including itself, and your board might or might not work.