Sounds like this might be specific to your brand of TV. I have a Sony and there's a bunch of Sony junk on there that I disabled a long time ago. But my TV app doesn't have any ads in it yet. I'm guessing your manufacturer added ads to their TV app and made a deal with Google to use them as the ad provider. Unfortunately, those apps are relatively proprietary since they are supposed to be primarily just a simple UI for the tuners and so mostly hardware specific. Not saying there aren't replacements, but likely that would require someone to reverse engineer some of of the hardware firmware's APIs rather than web APIs that most apps interface with and aren't guaranteed to be the same across models. Those are only available if you own an actual TV, so it's less likely to exist.

Anyway, my point is that your searching probably needs to focus on the TV rather than the Android/Google TV platform as a whole. Look on forums devoted to the TV brand. You may have more luck.

The other alternative might be to block the ads on your router, but that may or may not work or cause some unintended inconveniences. For example I have Google's DNS blocked and my wifi constantly drops and reconnects even when I only want to watch locally hosted content because the TV thinks it's offline and needs to fix the connection.