There are things like torrentio now which lend BitTorrent piracy a more integrated UX, and that has definitely extended the lifespan of its usefulness to me. Torrents rarely max out my line speed these days, mostly because I have 1000X the bandwidth compared to when I first started torrenting 20 odd years ago. But it’s still one of the fastest and simplest methods to get any file you want, so I think it’s relevant
FWIW you can fix the aspect ratio issue on the firestick using ADB to force the device to display in a 4:3 resolution (except when using streaming apps that force 16:9)
If you want something privacy oriented you’ll probably need to build some kind of NUC. To my knowledge no off-the-shelf streaming device respects privacy