Apple has released beta 7 of macOS Big Sur to users participating in the beta testing programs for macOS. Usually a developer beta build is first and soon followed by the same build as a public beta version.
MacOS Big Sur remains in active beta development, while iOS 14, iPadOS 14, tvOS 14, and
watchOS 7 have all been finalized and released to the general public.
Any interested Mac user can install the macOS Big Sur public beta on any macOS Big Sur compatible Mac, though it’s worth remembering the beta system software is buggy and less reliable than stable versions. Therefore it’s generally only recommended to run beta releases on secondary hardware, and by more advanced users.