@ogredale I do not own a Fedora Linux.
After you created a PWA, the desktop association should be on Desktop.
If you hover the icon and open context menu Property โ Program you can see command and command line arguments.
As is se on my Debian the command line to a PWA can be for example:
/opt/vivaldi/vivaldi --profile-directory=Default --app-id=ooneffjahgdnmeoplmajpldbabdbnlhf