I have an Nvidia Shield TV. With 150$ its outside of your price range, sadly.
But: I've been running this thing for 7 years now and its still trucking. Compared to other smaller streaming sticks that have become unusable because of bloat firmware updates over time.
You can install custom firmware on it, but my understanding is that when you want streaming apps like Netflix or Disney to give you more than 720p output, you need the official OS.
If you want to Dodge the ads on the launcher, there are alternative launchers that can simply be sideloaded.
I don't use Jellyfin but I have all my movies on an SMB share that I'm accessing via Kodi. The hardware is strong enough to decode any format you throw at it.
You can use kodi on any old computer or a kodi device like Vero that uses OSMC. There are non official apps for most services. Some take a little time setting up, others just username and password. While kodi its self might not spy. The streaming services certainly still track what you watch.
I went for an old small PC so that I can get 4K on Netflix with Edge (most Android box tops at 1080p or less, I don't remember, because they are not certified by Netflix).
I can watch YouTube videos on piped.com, use a VPN to watch contents available only in other countries and in this way no one is spying on me.
@om1k@sopuli.xyz
How do you force Smarttube as default?
I uninstalled the default YouTube app, but if the device suggests a YouTube video and I click on it, it tries to install YouTube instead of opening it in Smarttube.
If you don't want to write out a lot of instructions but have a link to someone else's instructions, please feel free to do that...
SmartTube -> Settings -> About -> Enable global search (firmware support needed)
If you click that it will download a app which will function like a gate (it places it in instead of the original YouTube app which it deletes) and sending everything which normally goes to the original YouTube app to SmartTube instead. So global search works, the promotional stuff on the homepage also gets opened in SmartTube and so on.