Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Excel 2019 was released September, 2018 The version history is here:
Update history for Office for Mac | Microsoft Docs
Excel 2019 is "Sandboxed" meaning that it adheres to Apple's security guidelines. Personally, I see no advantages to sandboxing, but Apple and Microsoft do. Sandboxing breaks a lot of stuff. One app can no longer control the OS or other apps as easily. There's lots of "Grant Permission" dialogs thrown by Mac OS when your app tries to open or save files. You can't do anything about this. I think the biggest benefit to Apple regarding sandboxing is that it breaks Microsoft Office.
Problems with Apple’s sandbox ... - Ron de Bruin
In terms of the feature set, very few features were lost from 2011 to 2016 to 2019. There are many new features that you can take advantage of programmatically. In this regard, your code will run into almost no complications. If you run into sandboxing troubles, see Ron's page for advice.