WSL 2
How to mount a Linux Virtual Hard Disk
wsl -d <Distribution> --mount --vhd <path>\ext4.vhdx
If you get the error:
The process cannot access the file because it is being used by another process.
Then use Diskpart from a command prompt running as Administrator to detach it. Otherwise, reboot and try again.
diskpart
list vdisk
select vdisk file="<path>\ext4.vhdx"
detach vdisk
exit