[ognarb]

Maybe you could take a look at Calligra Plan, it is one of the only part of Calligra still actively maintained.

https://calligra.org/plan/

[hcal]

Thanks for the suggestion. I did try Calligra Plan. I manage a lot of medium-small projects, and to ended up not fitting my workflow very well. That said, I could see how it might be perfect for people who manage and plan bigger projects.