From IndieWeb is a project that allows you to review anything at all, as long as it is describable by a web address (including OpenStreetMap or Wikidata entity, which cover pretty much everything on the Earth and off it). The software is in early days, but is built to be federatable (federable?); the API is open.

This seems prime for integration into an Indieweb blog or similar, as a review might be reposted on the blog, or a blog post might be a review itself or incorporate one as a centerpiece. Even if this never happens, various parts of the indieweb (or the siloes if you're more low-star focussed :P) can be reviewed today! If you have an account, that is; right now, there is an invite system in place where 1 invite code is awarded for each review.

People you can ask for invites: Arlo James Barnes (2+ invite codes available)