Neo4j is really neat! I particularly love using its query language Cypher, it's pretty intuitive and easy to reason about. I've been using it professionally for a few years now and it's changed the way I think about some data -- it's basically like drawing on a whiteboard.
I was able to solve one of the days of the 2019 Advent of Code with just a few lines of Cypher without any other code.
It's not nearly as pretty, though. GraphViz graphical output gets very hard to read when the graphs get big.
I like that your setup makes it easier to drill down to the dependency graph of a single root package, too. pipdeptree will always show you the relationship between every installed package in the current Python environment.