I think what you want is either plex or Jellyfin which will give you a nice UI to browse your already downloaded files.
Now how do you browse new releases and figure out what you want to download? I just setup https://overseerr.dev/ to go along with sonarr, radarr, prowlarr, nzbget, transmission... it's a lot of different services but they all work well together. Now to look for new movies, I or my family goes to Overseerr to request downloads, then plex to watch.
Django is great, I've used it in a number of projects, both paid gigs and side projects. Where it really shines is giving you a nice admin to be able to do CRUD (Create, read, update and delete) operations on the database with minimal work on your end. If you don't need this, then something like flask is lighter weight and might be a better option.
However, while python has type hints now, it is still a loosely typed language. If you really want to the benefits that come with a strongly typed language, I'd suggest maybe looking at Rust, Go or even TypeScript.