Retention policies for modern team sites

Hi Max, 

             I am trying to prevent owners from deleting Sites. Also wanting to retain any data from the sites. When you say permissions should be the way to prevent deletion totally, what is the preferred method to do this? e.g. as an admin we create a Groups connected site and only give them member access to that group?

I am indeed creating a retention policy from S&CC and I can only see the root sharepoint site for the tenant. However I am aware that you need to add the full URL for an individual site if you want to add these but on this occasion it seems I can (as a Global admin) only add sites that I am a member of or owner of. I'm not sure if I am missing something but the whole admin side of the new modern site management seems a bit shambolic. 

One thing I noticed is that when a site is created by someone either via Teams/Outlook etc then the admin centre shows "Group Owners" as the primary admin. Makes no sense and as an admin we need to either add ourselves to the group as an owner or sift through the audit logs to see who created the site.

The overall goal here is to prevent normal users from creating the sites/groups themselves but at the moment I am struggling to see how best to manage these.

Thanks for replying.