Exclude items available on my selected streaming services from watchlist RSS feed

In order to be able to make use of Plex’s watchlist feature, I need to be able to determine the difference between items available to me via my selected streaming services and those not.

If only items not available on my selected streaming services are published on my watchlist RSS feed, then I can integrate with external media managers, only importing items I can’t already access via streaming services.

I have no current workaround meaning I can’t watchlist items available on my streaming services, which negates the main benefit of the omni-watchlist.