IMHO, Android still has the best ecosystem of TV remote navigateable apps. The problem is just Google.
I have a 'Google TV' android based TV.
It started out terrible, but after removing or disabling almost all apps and installing couple replacements, it's great now.
Most importantly:
- FLauncher replaces the Google launcher and thereby removes almost all ads and 'recommendations'
- TV Bro is a FOSS webbrowser for TVs that has build-in add-blocking
- SmartTube is a Foss YouTube client that just works great and brings Add- and Sponsor block
- Stremio with Debrid Media Manager and Torrentio (both using a Debrid service!) for streaming in general
- Jellyfin if you have a home server
All of that is FOSS and would work completely without Googles involvement, if you find a way to flash a custom ROM onto a TV or TV box.
Alternatively: Anything with an 'air mouse'.
An alternative to Android, I have used before, was just Linux with oversized app icons and then a G20s (Pro) remote. These cheap chinese G20s remotes work great as a mouse, similar to a Wii mote. Especially with the G20s Pro you can even set numerical passwords for everything and then just type it on the remote. They also have microphone that only works when you press the button. So if you have some tts service on you device, this is also a solution. I haven't found a solution for it yet, but I believe, using T9 typing as a text input would also be a great solution when using these remotes.
There are also air mouse with a full keyboard built in, like the W1, W3, Q40... But I think, they are all a bit too heavy and too big, feel clumsy at the slight benefit of having a keyboard.
And then there are devices like the A8, which are just small keyboards with a touchpad, that also work as an air mouse, but fail as a remote IMHO. But that entirely depends, on how much typing you want to do on your TV.
Stremio is basically just a foss streaming app that doesn't do much and relies on customization through extensions. There are extensions that add streaming services and extensions that grab recommendations/popular series & movies from different sources. The basic idea is, that you should connect all your streaming services to it (through extensions) and than add stuff like rottentomatoes and IMDB to it, to get recommendations. Then you select or search for whatever you want to watch and Stremio shows you, which of your connected services has that particular stream available. Technically completely legal and fine.
However, it's often (ab)used for streaming directly or indirectly from filesharing protocols. So, instead of adding Amazon Prime or Netflix extensions to it, which discriminate against FOSS clients by only delivering low-quality streams, you could add something like Torrentio. Torrentio is an extensions that can use various torrent trackers (both free, insecure ones, like 1337x or Piratebay, as well as private trackers) to look for available torrents for the thing you want to watch and then it acts as a torrent client and streams the video file directly from that torrent.
Torrentio can also be set up, to use a Debrid service. A Debrid service, is a cloud service that acts a bit like a cloud storage that can download files from torrents or filesharing sites (often through a premium subscription at that service, that you don't have to buy yourself) and then allows you to download these files from the cloud storage. Most importantly, it decouples you from the torrent, acting a bit like a proxy or VPN, and keeps your IP safe by doing that (e.g. to avoid law enforcement). It also allows you to start a torrent download that has few seeders and then let it run possibly for weeks and get notified, once your Debrid has completed the download. And lastly: a good Debrid service basically 'seeds' the files other people have downloaded on that service to all other people on the service, that request the same file. (We call that 'cached') Through that, you can get most popular torrents in a matter of seconds, which effectively allows you to stream them fast and reliably, like from any streaming platform.
Again, Torrentio can use a Debrid service like that, which makes it secure, reliable and convenient. A really good Debrid service should cost around 3€/month and will have basically all films and shows from all big streaming platforms (Netflix, HBO, Prime, Disney,...) already cached in 4K HDR+ Dolby whatever. This basically offers you a much better service than any other streaming platform, doesn't serve you ads, preserves your privacy and does all of that for the small cost of 32€/year and living in a legally dark grey area.
Torrentio has a small flaw, when used with a Debrid: Torrentio uses torrent trackers (1337x, NYAA, EZTVx...) to find a fitting torrent and then requests that from your debrid service. If you are lucky, your service has that torrent cached and you immediately start streaming. Otherwise, your debrid has to start downloading the torrent and will only serve it to you a while later.
An alternative extension for Stremio is Debrid Media Manager (DMM). It basically tracks, which files are cached on your debrid already and then allows you to specifically request those already cached files, making it start the stream more reliably. However, most debrid services don't really like having their cached files tracked, for legal reasons, and sometimes close or obfuscate the API, which makes DMM a bit less reliable on some debrids. Then again, the Torrentio service that downloads tracker information also likes to fail sometimes.
I have both installed (using the same debrid) and default to DMM and only check Torrentio when DMM fails. Other people have it the other way around.