[Multicomp]

I vouched for this because while it does not relate to using markdown to create gantt & timeline charts, it does relate to using code to create said charts and is therefore IMHO a relevant comparable tool.

See https://mermaid.js.org/syntax/gantt.html and https://mermaid.js.org/syntax/timeline.html

Having said that, it's late tonight but I plan to give this markwhen a good look tomorrow when I'm fresh, because even being aware of the above options, I've not found an offline friendly code-to-timeline tool I can settle on and this may be it.

[zmmmmm]

PlantUML does Gantt charts too completely off line if you want. Kinda ugly but surprisingly powerful. I have managed whole giant projects this way.

[Multicomp]

Thanks for the idea, I hadn't considered checking if PlantUML could do that...that's what I get for pidgeon-holing that tool for hierarchical state machines I guess.