2 – You can create a custom widget with any third party javascript Library for Gantt Charts (e.g. http://jsgantt.com/)
The on-Premise Version contains more Widgets, especially if your company has a SAPUI5 License. Furthermore you can always build your own Widgets by extending existing UI5 controls. (you can find it in the docs https://community.simplifier.io/doc/previous-release/#11181)