We have about 40 mailbox-enabled rooms (meeting rooms). All of them have resource delegates assigned. The company grows rapidly and the delegates change very often. This not only puts a load on our help desk but also the more rooms and changes there are, the more mistakes creep in.
To ease this up, we created Office 365 groups and assigned those groups as resource delegates on the mailbox-enabled rooms.
Afaik no. Even if you can technically add a group to the relevant property, the functionality will not be available as you've noted already. You can easily script a solution that goes over the list of rooms say once a week and adjust their delegates based on membership of some group.