There are "Navionics chart sets in S63 distribution format" available from ChartWorld. This is correct.
We can't confirm that the content of these charts is identical to Navionics charts for plotters or their App chart sets as we don't have the details. Or how they differ.
And there are OCPN users who licensed these charts.
These charts are bundled by Chartworld on base of content delivered by Navionics as an alternative for sailors that don't require official charts.
In the beginning of the S63 plug-in users reported problems about some features not displayed rom these charts and it showed up that Navionics was using some propietary S57 objects. We had contact with Navionics about these issues and tried to repair the situation. Then the communication from Navionics side ceased.
We don't have information if they have solved
these issues. Feedback from people who licensed S63 ChartWorld Navionics sets lately would be interesting.