Yes it requires you to download before streaming, because specifically torrent-streaming, i.e. streaming the torrent chunks as they download only leaches and is pretty negative in the p2p community. Im part of a private tracker and always seed back.
My grandmother can connect to my jellyfin just fine with her roku and shes the least tech savy person ever so I dont feel like the “wife-proof” holds water. Jellyseerr or Overseer (for plex) lets people request content in an app friendly manner. Theres things so your friends or family can access your content without touching the bones underneath.
No jellyfin is bare bones open source streaming app. It does have addon support, but no Netflix or hbo. But i dont subscribe to any actual streaming services, because i don’t need them because of my Arr stacked Jellyfin. However an Arr stack server with Plex as the headend could do what you’re asking.