Extension:Interlanguage is very helpful when the Wikidata item exists already or when it doesn't exist yet but there exists any other-language page of the same project.
I request to extend its function also to easy creating of missing Wikidata item for all other cases:
- to join inteproject link (using project code instead of language code, e.g. enable "c:" instead of "en:")
- to create and open item page easily also without any inter-site link (for edit of statements, possibly also for automatic export of statements from infoboxes and tags if implemented)