I missed that one - likely tired 
- I have amened the PKGBUILD and now it takes care of the passwd script as well.
I will check on a pi with a desktop now.
When I got the copy of the password prompt right - forgotten how install worked - I tested on a Gnome desktop - and it works as expectd - I don’t know if gvfs is strictly required - if it is it should be moved to depends instead of optdepends.
Testing using minimal manjaro CLI (with added lxqt desktop) - I found that gvfs is required to register change in attached devices.
Next I found that setting new guids would fail because uuid is not a known command on arch but uuidgen is.
The updated PKGBUILD has been uploaded to AUR [1] so you can do
git clone https://aur.archlinux.org/piclone
cd piclone
makepkg -is
The last thing to test is the Could not set flags message - this is caused by the code setting lba flag on a non fat32 partition - it can be ignored.
The app will also try to eject the target but it will fail because it is assuming lxde - which is the default environment for raspberry pi os.
So I am looking at using udisksctl instead.
All this will require yet another patch - which is a challenge in itself - as I have absolutely no knowledge of C language - it looks familiar though so … one is optimistic
final patch arrived - everything works now