esp devices are generally super easy to replace the firmware on. I have PetLibro Water Fountains that use a weight sensor powered by a esp32. I opened the base,

esp devices are generally super easy to replace the firmware on. I have PetLibro Water Fountains that use a weight sensor powered by a esp32. I opened the base, attached three wires to the uart output on the processor, flashed esphome firmware and loaded it into home assistant, completely cloud free monitoring. The undocumented instructions isn't a backdoor at all, it requires you to have local access or have already taken control over the firmware via another bug. The only thing that people going nuts over a "backdoor" will do is cause espressif to close up their interfaces, which would make it harder in the future to repurpose the hardware.