Samsung uses this for their Knox security feature. The fuse gets broken in initial bootloader unlock, and all features related to Knox (Samsung Pay, Secure Folder, etc) gets disabled permanently even after reverting to stock firmware.

There are not. The entire premise of eFuses are that after you buy something, the manufacturer can still make changes that you can't ever undo.

I use them in an esp32 to write a random password to each of my products, so when I sell them they can each have their own secure default wifi password while all using the same firmware.

eFuses are in most CPUs, often used for things like disabling hardware debug interfaces in production devices - and rollback prevention.