Gerry Hampson Device Management
We've been able to do this for quite some time. We've been able to add individual users as local administrators on Azure AD joined devices. More recently this has become a lot easier. We can now use Azure AD groups to manage this. With Azure AD Premium P1 or P2, you can create a role-assignable group and assign the Device Administrator roles to the group.
There are some additional considerations. Firstly, you can only configure a group to be role-assignable when you create the group. You cannot change this afterwards.