On the wiki page:https://wiki.dfrobot.com/FireBeetle_ESP32_IOT_Microcontroller(V3.0)__Supports_Wi-Fi_&_Bluetooth__SKU__DFR0478I found informations:"The output voltage of the pin VCC is equal to power source's voltage. (Output USB voltage when powered by USB, output battery voltage under 3.7V lipo battery input)The VCC port usually is not used as the power supply port of the mainboard. If you have to use that port to power the mainboard, then the battery input pin should be left floating."

So it should be possible to power the board through the Vcc pin, but I should leave the battery input pin unconnected.