I feel like Bookwyrm has proven the idea of a federated review platform. Could this be extended to local business reviews?
I vowed long ago to stop contributing to closed platforms such as on Google Maps or Yelp. Could a federated alternative be a good solution?
I think the main difference between a small Bookwym instance and what you propose is that a business review site only becomes useful at a much larger scale and risk of someone manipulating it is also much higher.