I am not aware of any creators who get sponsorships paid in impressions. Albeit, I don’t really talk to anyone who goes hard on tiktok or instagram so there is that.
But it is not at all uncommon for a sponsorship deal to include some metrics. They want to know retention rate, how often people skip past your sponsor bits, etc. And youtube DOES record that. Many videos will have a little chart if you mouse over the tracking bar that shows the most rewatched portions.
And if you can demonstrate that people tend to actually watch your sponsored segments? You often can get a MUCH bigger check. Its why a lot of mid-tier creators will do a skit for their sponsored segment. And why the really big ones completely phone it in because they know the vast majority of their watches are people who can’t go to sleep without having Ninja talk about how he can’t be around women who aren’t his wife.