Office 365 Group Expiration and SharePoint Group Connected sites

You define the policy and can add them to all, none or selected groups. This means as soon as a Office 365 group is created (from all those self-service buttons), the underlying group is added if this is set to all.

We managed it several times now in projects to define the policy for selected groups and create processes with Forms/Flow/Approval/Azure Functions (PowerShell) to distinguish permanent ("admin") groups from those adhoc groups that people can create on their own. Therefore we run a script every night which puts the new groups that are not adhoc-groups into the new policy as a Azure Function with a timer trigger. Adhoc groups are put into the selected groups for expiry, other groups are not afected by this (and miss also the default naming convention as the PowerShell runs with appropiate rights to overrule the policies).