bypass magic mouse after OS upgrade
I am trying to upgrade my iMac Pro (currently on High Sierra OS), and have made a copy of my OS onto an external hard drive as a safety backup. When I try to boot up from the external drive, I see flashing icons for the wireless keyboard (which I have) and the magic mouse (which I do NOT have). I can't see a way to get past these icons, which appear to suggest that the external hard drive OS is telling me to turn on and pair the wireless keyboard and mouse with the OS. I am worried that if I do an OS upgrade, I will not be able to operate my iMac Pro if I can not get past these icons.
At this point, I have not made any changes to my OS (still on High Sierra) and everything works as expected. I can't risk loosing control of the computer if the OS upgrade fails. Any help with this would be greatly appreciated!
iMac Pro, macOS 10.13