This article describes how to block welcome messages for new members of Microsoft 365 groups using a resource behavior option (a group setting). This is an immutable setting that prevents the Groups service sending welcome messages to new members. You might want to take this approach when creating team-enabled groups.
The Microsoft Graph SDK for PowerShell includes cmdlets to create Entra ID Groups and manage those groups afterward. The cmdlets work and in some places they are screamingly fast compared to Exchange Online or Azure AD cmdlets. In other places, the cmdlets are a tad bizarre and expose a little too much of their Graph underpinnings. Oh well, at least after reading this article, you’ll know where the holes lie.
It seems like it should be possible to transfer a membership rule from an Exchange dynamic distribution list to a dynamic Microsoft 365 group/team, but it’s not. Different directories, schemas, properties. and syntax conspire to stop easy conversion. It’s a pity, but that’s the way life and technology sometimes go…