I think there is almost no chance Apple will offer an optional bootloader password. It's not a great Ux for one thing. Another is how does the user do a reset?

I think there is almost no chance Apple will offer an optional bootloader password. It's not a great Ux for one thing. Another is how does the user do a reset? In case they forget the usual unlock code, the consequence is they lose everything on the encrypted volume, including their data, but not the OS itself which just reverts to a "first boot" requiring setup from scratch. What does this look like when the bootloader chain is encrypted, presumably including all or critical parts of the OS itself? That's non-trivial.