WinSXS looks like a huge folder in explorer, because explorer's size estimates do not tell you about hard links. It's not that big. I need to question somebody who thinks removing it will remove a lot of bloat.
Get the size of every “file” in the volume along with the file id of each and then subtract the size of any files with a matching file id that are in the WinSxS. Then sum the size of the remaining files that were from the WinSxS.
You can get the file id using https://learn.microsoft.com/en-us/windows/win32/api/winbase/... or fsutil, etc.
You could also probably execute “fsutil hardlink list” for every “file” in WinSxS and then ignore any that list more than one result and sum the size of the remainder.
There are of course more efficient ways to do this but those are some quick hacks.
dism.exe /Online /Cleanup-Image /AnalyzeComponentStore
Any space reclaimed using dism’s startcomponentcleanup is only from removal of superseded updates which normally happens automatically whenever the maintenance task runs after a certain period of time.
Note that I explicitly consider backups separate from superseded updates. Superseded updates are kept for a period of time to allow the user to uninstall a newer update.
The remaining content unique to WinSXS is either for cryptographic validation, app compat, or the driver stack.