This is the setup I've built so far:

I use KonstaKang's LineageOS Android TV build running on a pi 5: https://konstakang.com/devices/rpi5/LineageOS23-ATV/

No Google play services store at all, I just use ADB to install apps

This is the launcher I use, it's way nicer than the stock Lineage one: https://github.com/meddouribadis/arclauncher/

I use SmartTube as my YouTube client: https://github.com/yuliskov/smarttube/

I have this Bluetooth remote app on my phone for the rare occasion I need to type a password or something: https://f-droid.org/packages/io.github.jqssun.btremote

I also have KDE Connect on both my phone and TV so I can play/pause media from my phone at any time and send files (like new launcher wallpapers) easily without adb.

There's no best answer right now, Plasma Bigscreen is making good progress.

I have to imagine they'll soon be putting cellular antennas in the TVs to circumvent all that anyway.

Old laptop, debian, Firefox, g60s remote. Done.

Im on a 2013 m93p thinkcenter tiny. Still goes hard

Not a popular answer, but Apple TV is the best out of the box experience. Zero ads, massive longevity. Mine is like 7 years old and still running the latest tvOS.

If you have the cash and inclination, Nvidia Shield is the hackers choice. Zero hardware upgrades in years tho, but software aplenty.

Just don’t let your smart TV access the internet in any situation, there’s no need. It’s just a stupid display.

@Epzillon
I use #LibreElec with #Zattoo and #Netflix addon on an old Laptop. For remote control, I use a Remote with Bluetooth and Infrarot.
Currently I play around with #GamesOnWhales and its fork #Quasar for game streaming.

check out: https://plasma-bigscreen.org/

@Epzillon I have been using Plasma Big Screen for a while now and cant be happier. I use Jellyfin as my main media source, Fred TV for my IP TV service and PWA for Youtube and Netflix. My TV has been disconnected from the internet for a while now and I dont feel my kids know the difference. I also use the Rii bluetooth remote to access Plasma Big Screen interface.

A raspberry pi running Kodi has been serving me well for years.

Easy install paths include LibreELEC and osmc. I believe both are based on debian.

FWIW I chose and have been happy with osmc.

Regardless of the choice, Kodi has a plugin system for things like YouTube, you can access your media via the jellyfin plugin/app, or by pointing Kodi at your media. It has a remote app available on android and iOS, and for the most part just works.

Also, looking towards the future or for people that can find one at a decent price:

Not a raspberry pi but an Orange Pi Plus or Pro. They have a rockchip that has AV1 decoding (along with standard others) which is probably going to be the future (it is for corpo streaming already).

Put plasma big screen on it and get a Bluetooth wechip remote or something

Open the TV and pull the wifi antennas off the board.

For the real "TV feeling", try ErsatzTV. It basically creates multiple real-time streams of TV shows and movies from your media library. You can switch between them like channels.

Hey welcome to the hobby!

We personally have the whole TV on a Vlan, so it can't acces anything at all. While our server/HA can still send a WOL command to it, and jellyfin can stream our movies to it. I run all of it on top of TrueNas, most as an app or else an VM.

I have never tried to set something up for YouTube specifically, since that runs on a Chromecast (for now...)

Let me know how your journey goes

Me personally, I just use a Linux distro (ive used Ubuntu and popos, both have been fine) and use whatever flavor of streaming service I can access. Sometimes you're hit with lower resolution but I'd rather that than get spied on and be fed ads by my hardware.

Ive also gone back to physical media and use a DVD player. I'm just buying series I like one by one.

This video used a combination of physical media and streaming services. They relied on waydroid and with some workarounds, it worked well for them:

https://youtu.be/nROKp0BpFek?is=GFhDrr82dCCFGcVT

Two approaches:

Network isolation/DNS blocking - put the TV on a VLAN and only permit specific ports through to a media server (whatever the TV will support). If you lack VLAN capability, run PiHole as your DNS server (it works best as DNS and DHCP, but that's just my opinion for things I like, such as proper name resolution for all devices).

Second option: (your idea with a Pi) disconnect TV from network entirely, then run something like Kodi (or whatever media center you prefer) on an old laptop, mini-PC, whatever, and have that device connect via HDMI. HDMI can passthrough the navigation controls from the TV remote (not guaranteed, but it's part of the standard). I looked into this a long time ago but the performance wasn't there yet. Today I'd probably try any distro and run Kodi on it.

Even my POS Samsung passes through enough of the controls to navigate Kodi on a 2017 laptop, while retaining power, volume, settings, etc for the TV itself.

My current setup is a Jellyfin server and Jellyfin client on the TV. I run PiHole with a blocklist for all the Samsung BS which has had the side effect of making the TV menus faster as it doesn't retrieve any "what's new" info from Samsung. Its actually kind of fun to monitor the FNS log and see the domains the TV hits, click Deny and see what breaks in the TV. On average about 30% of all DNS requests on my network get denied, and nothing of value has been lost. That's how much crap is being sent all the time.

Hope that gives you some ideas.

It's been a while for me (I don't upgrade things that work and I try to buy things that last a long time...)

But, Hotel Mode might still be a thing, and it might bypass some "smart" stuff on the TV

I used that to make my TV start on the correct external HDMI port for my MythTV instance running on Arch Linux (btw) with dual TV tuners in.

The TV is rarely used to watch live TV and it's certainly not connected to any networking.

Just another approach that I've not seen mentioned here