By week 18-2024 "Classic Outlook for Windows" offers an option to test the "New Outlook for Windows".
There is defacto a new Outlook version available which does not allow the installation of the CalDav COM add-in. This version will only accept to install web add-ins.
COM Add-ins will not be supported in the new Outlook for Windows but will continue to work in classic Outlook for Windows.
In the new Outlook for Windows, web add-ins are fully supported, with no additional work required from partners.