Another question. :)
So, I wonder: I want a set of default folders to be created automatically in the document library when I create a group site or team site in the tenant. Is there a easy way to make do this?
You can use a site script to trigger a Flow when the site is created. While it would be great if we could just use the Flow to create folders, flow has difficulty with connecting to sites via a dynamic url. So to get around this limitation with Flow, one solution is to create an Azure function, and have the flow call this function, passing in the necessary parameters, such as which site/library should have the folders created.
This doc walks through the above process, and also uses the pnp provisioning engine.
This doc walks through a similar process, but without the pnp provisioning engine
So no, no simple mechanisms at this point.
And of course, the above only works if the user remembers to select the appropriate site script on the drop-down when creating the site. So, another option is to create sites for the users, and just script out the whole thing with powershell.