plenty of those - I've had to work with dozens of different graph databases integrating them on https://gdotv.com, save for maybe 1-2 exceptions in the list of supported databases on our website, they're all production ready and either backed by a vendor or open-source (or sometimes both, e.g. Apache AGE for Azure PostgreSQL). There are some technologies that have been around for a long time but really flying under the radar, despite being used a lot in enterprise (e.g. JanusGraph).