I just opened the Roku app. There's a small ad that's mid-screen on the home page, and other than a "sponsored" MAX ad that you have to scroll down to even know it's there, there's no other ads on the home page. There's no ads on the Search, Devices, or Account page. Yes, there's a small "My Roku" at the bottom of the remote screen. But unless you swipe it up it shows nothing. I don't consider that "intrusive" at all and can easily ignore it. It doesn't impact the function of the remote buttons at all.
I don't consider the ads excessive or intrusive at all. People can certainly feel differently. But compared to what I see on so many web sites and even phone apps, this is next to nothing.