Sources can be "Wikipedia" and 'References' in Wikipedia.

I'm not in favour of importing each article one by one by users.
Instead, Lunyr can use a bot that does that. Bot can also ignore controversial topics, automatically add references at bottom, etc.

The imported content may be edited by reviewers.

Afterwards, new content from publishers could replace the articles of Wikipedia.

This way Lunyr would become big enough for users to shift from Wikipedia to it. So, more publishers would be interested in published new matter on Lunyr as it would have a good user base.

This I think is a better solution to the chicken or the egg problem.