I recently reverse engineered an e-waste STEM toy from scratch ( https://github.com/padraigfl/awesome-arcade-coder ) and the general response I got from places were:
a. to salvage the microcontroller and other relevant parts (probably worth $4 off a board that would cost $100+ to replicate)
b. a weirdly hostile attitude about the ethics of reverse engineering regardless of the motives (guessing people have been burned a lot with people stealing their designs)
I've mostly worked on the frontend and don't have much knowledge of embedded systems at all but it wasn't anywhere near as hard as I expected. Keen to find some other ESP32 devices to tweak (suggestions welcome!). I guess even if making them unflashable becomes the norm it won't be too hard to just swap the ESP32 off the board with a new one.
It's not a particularly common thing yet, but smart home enthusiasts are becoming increasingly concerned about the expense and effort required to replace cloud-dependent hardware because the manufacturer decided the cloud service isn't worth maintaining anymore.