I think decypharr might do what you want, it simulats a qbittorrent client to connect to debrid.

No debrid support, this is for connecting to the Arrs services which work for either torrents or usenet.

sonarr and radarr only have support for a single account wich among other things exposes api keys.

Seerr lets you have users with the same login as they use for jellyfin (or plex?) To request content and the server admin can approve or deny rhe request.

20mbps is enough for most things. It mostly limits how many peoppe you could share content to at once, but even then if you had say 4 people you wanted to stream a movie to jellyfin has options so you can limit each stream to 2mbps or whatever ends up working best.