There’s a suggestion which is trying to address this. The OP of that suggestion is asking for an option to add items from Plex’ Discover to a local library. That library entry is supposed to point to a specific/selected streaming provider.
So in your example…
- you search for a movie in Discover
- you check if it’s available on Apple/Google/Amazon using the Where to Watch hub
- Some new option / context menu item on the streaming provider link to allow you adding the item to your library
- Clicking the item inside the library should bring up the provider app / web page for that movie / show / …
