Please add this warning to the general instructions:
I have confirmed on my MacBook Pro and my Hack. The drive that you want to install PB5 must be pre-formatted to Apple format. If you try to use an unformatted disk, it will not show as an available disk. If you try to use a recycled disk with a non-Apple format, it will show, but once you try to format to Apple it will error and remain in an unmountable state.
Even after post installation this is true. Basically, Disk Utility does not work unless the drive is already formatted to an Apple format. Fortunately, USB drives in exFAT for FAT32 work fine unless you try to re-format those to Apple.
I wasted so much time wondering why my brand new EVO NVME drive wouldn't show up for PB5 installation. I assumed this was due to hardware incompatibility but installing and using PB5 on my MacBook Pro finally solved the mystery. I think most folks use recycled Apple drives for PB5 so that should be fine as those are already formatted for Apple.
Edit - PB6 has same issues.