Is there any formal/official documentation specifically on the "modern template" functionality available in SharePoint document libraries? This page (https://support.microsoft.com/en-us/office/set-a-custom-template-for-a-sharepoint-library-8e0177eb-4...) tries to cover the topic for both classic and modern libraries and, as a result, is hard to follow and quite confusing (even to me, and I've been working SharePoint since MOSS 2007). I run a SharePoint workshop every month and since that feature has appeared, I've basically told folks: "so, there's this thing where you can upload a template, but there's no real guidance on how to use it, so let's just skip over that."
What we (and users) really need to know is:
Why would someone want to upload a template to a library?
How do they create a compatible template to upload?
What capabilities does this enable? For example, can document properties, such as column values from the library, be surfaced in the document? (I know this was possible in SP2010 with custom "document" content types)