The use case for this is that some websites may sell direct ads or sponsorships on their website. There would be a partnership page with info on the sponsorship package, as well as the website traffic, to help the ad space buyer judge its worth. But the traffic has to be added manually by the webmaster, or an automation has to be coded between that page and their analytics tool.

Right now I could not find a tool for publicly embeddable analytics. But what if this was Ahrefs Web Analytics? Just a limited version of the first panel would be enough to show monthly data for the past 3 months. And you'd get some brand awareness for your analytics tool.