They run near stock Android TV with very minor changes, really only Nvidia specific additions for upscaling and game streaming.

In comparison, you can use Steam Link App with Apple TV to stream anything, and it works perfectly. 300 hours Elden Ring used for testing.

Oh. Do the changes including removing the ads? OP said they get no ads, but perhaps they were mistaken...

No, they don't. It uses the stock launcher, which had ads added to it a while back.

You can use a different launcher like Projectivy instead, though.