In this replay of the SAP Community call: Add-On Uninstallation Process & Simulation Tool held on June 25th, Masoumeh (Mahin) Moghaddam covers how the uninstallation simulation tool supports you to find out what needs to be done to make your add-on uninstallable, to get an idea of the affected objects and if they can safely be removed. Her presentation is also available here: https://www.sap.com/documents/2020/06/5c90e646-9f7d-0010-87a3-c30de2ffd8ff.html

You can read also more about it in the blog post of Karin Spiegel: https://blogs.sap.com/2020/05/12/need-help-to-get-rid-of-an-add-on/