To rephrase: the sharing plugins that are loaded into the sharing dialog are having lots of permissions. It’s not possible to limit the access of a binary plugin loaded into a process.
And because of that we have been implementing a separate mechanism to register applications to be used for sharing. Those will be also presented on the dialog’s method list and if the user chooses such, the app will be launched to handle the sharing further. This is something we can even allow in Harbour.
But both of the mechanisms will remain and technically there shouldn’t be obstacles in keeping using custom sharing binary plugins. They are just not going to be harbour allowed.