Yes they do. Usually one big ad on the side of the screen. And they may if you use certain screen savers. I think the city scapes one puts ads in it. Note: all the ads I mention are static images without sound.

Hoo BOY does Roku have ads! When I installed PiHole on my network and used it as my local DNS, the TOP blocked domain was “scribe.roku.com”. It was calling home like 5000 times a day. We were thinking every single remote push maybe.

Blocking those domains made the entire interface speed up drastically, and got rid of the giant box ads on the side as well. (It’s just a big empty frame now lol).

Rokus are nice and cheap if you can mitigate their rampant data harvesting.