Installing macOS Big Sur 11.0.1 appears to be causing issues for those with older devices. In particular, those with older-generation MacBook Pros seem to be affected.
Old MacBook Pros Bricked by macOS Big Sur
One user with a 15″ MacBook Pro running macOS 10.12 posted on the Apple Support Forum that their device “won’t boot” after trying to install macOS Big Sur. There were replies from other users who had experienced this and other problems, including Kernel panics. MacRumors noted “that the overwhelming number of users experiencing problems are owners of the late 2013 and mid-2014 13-inch MacBook Pro” so those users, in particular, may want to hold off installing the latest operating system. It’s worth saying that for many others, myself included, the transition to macOS Big Sur has been a smooth one. Do however check out the support forum if you have any concerns.