I'm impressed with the grid diagrams too. I'm not sure plantUML has anything equivalent.
It doesnt support all the diagram types plantUML does (for now) but it has the only two i ever used anyway. The tooling seems more robust and modern. I think I have a better chance getting my coworkers to try this one
There are a lot more specific shapes and layouts in a flowchart than simple boxes and arrows. E.g. start and end, branching, loop back, subprocess, etc