I'm building https://www.ergodic.ai - and we are using a graphs as the primary objects in which the intelligence operates.

I don't think every graph needs a graph database. For 99% of use-cases a relational database is the preferred solution to store a graph: provided that we have objects and ways to link objects, we're good to go. The advantages of graph dbs are in running more complex graph algorithms whenever that is required (transversal, etc) which is more efficient than "hacking it" with recursive queries in a relational db.

For us, I've yet to find the need for a dedicated graph db with few exceptions, and in those exceptions https://kuzudb.com/ was the perfect solution.