Can you replace the bootloader of Android to create a UEFI-like environment where you can Multi-boot into another Operating System? I've seen several off-brand phones do this but I'm unsure how they do it. There is a phone on the market
(I think on Amazon) where users report that their phones don't directly boot into android but give them a choice of booting into "Android Core" and "Android OS". If you can actually do this, is there a way of flashing this ROM onto a phone, or are there other steps needed to accomplish this task?