Clean Install Big Sur/Windows
a)	Use Boot Camp Assistant to delete Boot Camp partition
b)	Reinstall Big Sur
c)	Use Migration Assistant to restore MacOS apps and data.
d)	Use Boot Camp Assistant to install Windows 10 v. 20H2.
e)	Use Windows System Image to restore Windows 10 apps and data.
f)	Installing Windows System Image erased the Big Sur partition!
g)	Use Migration Assistant to restore MacOS apps and data.

~$ diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *4.0 TB     disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                 Apple_APFS                         50.0 GB    disk0s2
   3:       Microsoft Basic Data OSXRESERVED             10.0 GB    disk0s3
   4:       Microsoft Basic Data BOOTCAMP                1.9 TB     disk0s4
   5:                 Apple_APFS Container disk1         2.0 TB     disk0s5

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +2.0 TB     disk1
                                 Physical Store disk0s5
   1:                APFS Volume MacOS - Data            365.3 GB   disk1s1
   2:                APFS Volume Preboot                 292.4 MB   disk1s2
   3:                APFS Volume Recovery                613.8 MB   disk1s3
   4:                APFS Volume VM                      1.1 MB     disk1s4
   5:                APFS Volume MacOS                   15.1 GB    disk1s5
   6:              APFS Snapshot com.apple.os.update-... 15.1 GB    disk1s5s1

/dev/disk3 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        +949.9 GB   disk3
   1:                        EFI EFI                     209.7 MB   disk3s1
   2:                 Apple_APFS Container disk4         949.7 GB   disk3s2

/dev/disk4 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +949.7 GB   disk4
                                 Physical Store disk3s2
   1:                APFS Volume Backups of drou         353.8 GB   disk4s1