I realize it would require maintenance to stay current, but if you could collect (at least some of) your movies by streaming service, that would make it easier to shop and sync. For instance, I watched Wonder Woman 1984 last night on HBO Max using the app, and it was a great experience. If the app could let me know what other HBO Max titles I had in my library -- and suggest some I need to purchase -- that would be cool.
You could add a link to each service's page asking for help adding and removing titles and I'm sure you'd get it.

Your pal,
Craig