I have jellyfin with the radarr/sonarr/prowlarr combo going. I can “heart” things in jellyfin. But it’s recommendations are only things I already have downloaded. I see discovery in radarr, but no way to tell it if the movies I downloaded were good or bad. So I must be missing something.
Outside of self-hosted solutions, there’s JustWatch, which allows you to create an account, add movies and TV shows, and then you can rate them and get recommendations for it. It’s not FOSS, and you do have to create an account, but it does let you have a universal watch list for all services you own, and then see what people are watching and get recommendations.