Google's PageRank patent has expired (2019)
I'm not sure how useful this might be to anyone anymore.Google still uses it for the base ranking.  But, the results are then run through a variety of add-on ML pipelines, like Vince (authority/brand power), Panda (inbound link quality), Penguin (content quality), and many others that target other attributes (page layout, ad placement, etc).  Then there's also more granular weightings for things like "power within a niche", where a new page might do well for plumbing (because of other existing pages on the site), but wouldn't automatically have any authority for medical topics.