Reduces disk space taken by the WSL and Docker vhdx files

CompressWSLdisks.ps1

$ErrorActionPreference = "Stop"

$files = Get-ChildItem -Path C:\Users -Recurse -Include "ext4.vhdx" -Force -ErrorAction SilentlyContinue | Select-Object FullName, Length

wsl -u root fstrim /

foreach ($file in $files) {
	echo "Compacting $file"
	wsl --shutdown
	Mount-VHD -Path $file.FullName -ReadOnly
	Optimize-VHD -Path $file.FullName -Mode Full
	Dismount-VHD $file.FullName
}

Get-ChildItem -Path C:\Users -Recurse -Include "ext4.vhdx" -Force -ErrorAction SilentlyContinue | Select-Object FullName, Length

You can change wsl sudo fstrim / to wsl -u root fstrim /, saving you the trouble of messing with sudoers.

Another issue that may occur is if your admin account is different from the normal user account.
Then wsl won't find the installed distributions.

And execution policies may get in your way:

powershell.exe -ExecutionPolicy Bypass .\CompressWSLdisks.ps1

For some windows editions, you don't have the VHD commandlets, instead you can do:

$ErrorActionPreference = "Stop"

Get-ChildItem -Path C:\Users -Recurse -Include "ext4.vhdx" -Force -ErrorAction SilentlyContinue | Select-Object FullName, Length

wsl -u root fstrim /
wsl --shutdown

diskpart
# Type the rest in the diskpart terminal that just opened
select vdisk file="C:\WSL-Distros\…\ext4.vhdx"
attach vdisk readonly
compact vdisk
detach vdisk
exit

From microsoft/WSL#4699 (comment)

Yeah you can install them manually even on Home editions if you search for smth like "windows home hyperv install".