I know there's a lot of legal areas open source apps have to stay out of, like the reason none of these open source maps have good points of interest databases is because they can't just import in what google has, for legal reasons. But I feel like for reviews you should be able to click a checkbox that says 'show google reviews' or something for the end user, and just webscrapes it on demand for the business you're looking at.
Even better, there should be an anonymous torrent or something of both POI databases and reviews that you can import into the apps as an end user. That way the app creators are legally protected 'our app doesn't directly give the end user google owned data' but the end user just searches google finds the db file and imports it. Boom! Win/win