> Is this particularly different to an AGPL / commercial dual license?
The SSPL is based on the AGPL, with one section (13 IIRC) changed.
The AGPL requires sharing the software's source code with users who access the software over a network.
The SSPL additionally requires sharing any other programs used to install, manage, monitor, etc. the software when a service consists primarily of delivery of the software itself (eg. hosted database instances).