My TV has always been run without the "smarts" ever since I bought it.

That said, recently I've replaced my TV Box and Media Box with a N100 Mini PC running Linux and Kodi plus a wireless remote and in addition to that the thing even works as my home server with additional functionality than just that of the devices it replaced.

For a cheaper/easier option try LibreELEC on top one of the devices they support (check the downloads page or the Wiki for the list). It's basically a Linux distro with Kodi, so open and with none of the privacy intrusion risks of Android. The same kind of wireless remote (example - note that you don't actually need to use the keyboard on the back or the air mouse) also works here since it just relies on standard shortcut keys of media programs like Kodi so works everywhere (even Android).

However what all these privacy-protecting non-enshittified options have in common is that they're not fully configured solutions that you just buy and use - as you've noticed, if you just buy a streaming stick or device it will likely be at the least "spammy" - and you do have to do some of the work to get them working.

Something like LibreELEC on a mini PC should be the simplest to put together as the hardware comes preconfigured in an actual box and all that's needed is to install the LibreELEC image from a bootable USB stick, but if you have a bit more technical know-how (not really that much needed, mind you) you can get something like one of the supported Orange Pi boards along with a box for it and it will cost you less than half as much as even a basic Mini PC - those boards are basically using the same chips as Android TV media boxes so you get the same performance without the "spammyness".