The ESP32 does have internal pull-up and pull-down resistors on certain pins. I believe GPIO14 on this board maps to GPIO22 on the ESP32 chip (mismatched IO pin labels is bit of a pet peeve for me!) which does have pull-up and pull-down resistors that can be enabled. If it were me, I might tie the doorbell switch button from GPIO0 to ground. This pin has a pull-up resistor as it needs to be high to boot normally. So this has the added benefit that you can hold the button in when you first power the device to put it in flash mode, which also eliminates their "Make sure to get one with a “flash/download/io0” button" warning.

If you have an "old fashioned" 24VAC line, you could add a rectifier and buck/step-down power module to drop that to 5VDC. Or just unhook the 24VAC transformer and install a 5VDC one.

It would have been neat to see how much the RGB ring lighting up white helps in no/low light cases. All in all, nice writeup!

I wonder if the following would do the trick at line #47 [0]:

    pin:
      number: GPIO14
      mode: INPUT_PULLDOWN

This is a suggestion based purely on two minutes of web search, not on experience, though.

[0] https://github.com/thatguy-za/esp32-cam-doorbell/blob/main/e...

It's a pull-down resistor.