Might just be my ignorance- if it has boxes connected with directional arrows it does everything I need a flow chart to do

Oops i can’t read.

Flowcharts / activity diagrams seem well supported too, though.

Looks like it. https://d2lang.com/tour/sequence-diagrams

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

This feels like a more modern and feature rich version of PlantUML. Very interesting