We're currently discussing whether it's possible to use the activities recorded in a Case (including the scheduled activities in a timeline), export them into Excel and convert it into a Gantt chart, but I can't see a way to export all activities associated with a Case. When I look at the options in the Civi Reports, it will only export the most recent activity. Would Drupal Views be any use?
One thing that has annoyed me for years is the lack of a working Gantt Module or CiviCRM Extension. Due to the many ways people use Drupal and CiviCRM, I created an “Instruction Guide” (With Code Samples) rather than a module or extension.
You can get it here:https://github.com/jdgamsterdam/d9civicrmgantt
Yes, you would be able to do that with Drupal Views. There is also an extension that provides the Case Activities with the API: https://civicrm.org/extensions/caseactivity-api