Pixel owner here, since the Oreo upgrade I've had a red dot on my Google keyboard (on the emoji button) and when you tap on it you get what is basically an add for some thing that lets you make your own emojis or something. Haven't looked at it in much detail but it doesn't seem to be a Google owned app.
Lets face it though, Google is an ad company which tells you two things about them;
1. To them, you're a wallet with opposable thumbs.
2. Everything they do is done with the goal of propagating their advertising network into more places.
I sure hope the "pure" Android experience doesn't include ads.