- You can request in Seer and after downloading click the "Watch on Jellyfin"-Button, which then leads you to the movie. So its technically two separate services but feel like one. (With Seerr, Prowlarr, Radarr, a Downloading Client, Jellyfin and Bazarr its actually many selfhosted services but it doesnt feel like it.)
- With my setup through Radarr I need to download the whole movie. For series it depends it also meeds to download one whole file, then it goes through sonarr and then gets sorted properly into the library with metadata and coverimage and so on.
So yes, I cannot sit down and then decide spontaniously what to watch. But I currently dont work like that: I hear about a good movie somewhere, add it to the library. Then, after 10' to 2 days (depending on how popular it is) its downloaded. When I sit down because I have time to watch something, I then browse through the library, which I all know, that they are good and interesting movies.
If I have friends over, I ask, what they wanna watch, request it and we eat dinner and afterwards we watch the movie.

probably a jellyfin plugin which then hooks into the seerr service