I took an old laptop and transformed it into an Arch Linux based smart-tv (thanks to a stabilized "air mouse" and AwesomeWM to configure windows positions and shortcuts through LUA). Now I basically do everything through Firefox in kiosk mode: it's fast, you can avoid ads, telemetry et similia through configuration tweaks and extensions. The only problem I have is with Sky/NowTV services, that are not accessible by web browser and don't have Linux apps and are not (yet?) working through wine. All the rest I use (Prime Video, Netflix, Mubi, Discovery+ etc) work great with it, way faster and cleaner than usual smart TV apps. This with a 15W-TDP 4th-gen i3 based old entry level laptop.
That's just to say that Firefox can actually be pretty good for TV!