Bluetooth initializes very early in the Catalina boot sequence, I believe it is during the preboot, and you can do things such as booting from the recovery drive, safe boot, , etc. using an Apple wireless keyboard wirelessly. I haven't tested that with third party bluetooth keyboards so I cannot certify it would work with another manufacturer's product. If, for any reason, that does not work simply plug in the charging cord, and the Magic Keyboard magically becomes a wired keyboard.
I'm sure it goes back quite a few years, but I've got a very clear recollection that the answer to questions such as this one was that Bluetooth didn't kick in until late in the boot process and that a wired keyboard was necessary for boot commands.
Am I misremembering, or has the sequence of boot events changed for the better?
