IMHO Gantt charts in Calc or more often in Excel are a nightmare in terms of wasting time and still not having what is needed. I have seen so many people wasting a lot of time. Creating a Gantt chart in Calc or Excel was never an option for me.
In my strife to get rid of MS as much as possible, I looked around to open source SW replacing MS Project but did not find a really good one yet.
The best I found is LibreProject which was called before OpenProject. Accidentially or purposely???
The GanttProject mentioned by @horst, was new to me. (Thanks horst!) A first very quick glance on the demo video gave the impression that it is worthwhile to install and test the program.
My comparison standard is always MS Project because I used this program intensively. It is good. Maybe the best MS created. But there are also a lot of features in, which I never used. However, handling of the Gantt Charts, scheduling, rescheduling, splitting of tasks, linking various projects, and the import and export to Excel are great.
As for an enhancement request concerning Calc, I would not forward it. It will overload Calc and starting with a new Office component for scheduling will overload our devs.They do a great job with the current 6 components and have to fix quite a number of bugs and work on many enhancement requests.
Maybe LibO can put things together with LibreProject or the GanttProject to ensure a good import and export functionality to and from Calc. This something that I regards as feasible and also desirable.
But coming back to @SoWhy’s question, I heavily recommend him to follow the hint from @horst and try GanttProject or the LibreProject I mentioned. I expect that both are far from MS Project but much better than what can be created in Calc.