Starfish

Debian Stable as base OS, then activate unstable repos in a sandbox/container. Maybe even Distrobox for newer Apps.

How about miniPaint? Its mostly in JS.
https://github.com/viliusle/miniPaint

Maybe Piwigo: https://github.com/Piwigo/Piwigo

A german magazine just made a video on that topic. You can activate english subtitles.
https://www.youtube.com/watch?v=hBSEHpU-pyI
They tested a bunch of smart tvs and tv-sticks and their network activites.
They say that roku devices were the most privacy friendly tv-sticks.

And if you dont care about warranty voiding, open the tv and tape the things you dont want. Mic, cam, etc. Its probably the cheapest option

The closest thing to clean install is Ameliorated AME or Atlas OS. Check that out if you really need windows.

yes its warsow with bugfixes. They renamed it to avoid legal issues.