Media Directories UI provides media add form for core media types only. I propose to add ability to define own form for third-party modules same to Media Library:
function hook_media_source_info_alter(&$sources) {
if (isset($sources['my_media'])) {
// This is how Media Library add form is defined.
$sources['my_media']['forms']['media_library_add'] = MyMediaForm::class;
// Proposed solution for Media Directories.
$sources['my_media']['forms']['media_directories_add'] = MyMediaDirectoriesForm::class;
}
}
Active
2.1
Code