I'm trying to use an external drive to contain a Windows install and a Big Sur install, but I'm having trouble configuring the boot options on a MacBook Pro 2018.
I partitioned the external drive to have a Windows Partition and a macOS partition and installed rEFInd to the external drive in order to choose which partition to boot from.
This is the process I would like to have when starting up my Macbook: I would like to always boot up to macOS main install on the internal drive unless I hold option on startup, which would let me choose between macOS on the internal drive or to startup rEFInd, which will then let me choose an OS from the external drive (a second Big Sur install or the Windows parition).
Right now - I've managed to have rEFInd boot up whenever the external drive is plugged in, but whenever it's not plugged in the question mark folder pops up unless I press option to allow me to select my internal macOS install.
Anybody have any ideas on where to look to learn how to configure rEFInd or learn more about the booting process here?