In a nutshell:
No, unfortunately this is not possible at present.
Here are the details:
Due to technical reasons, it is not possible to assign individual of different subscription levels to different agents in the hosted Zammad version.
On the one hand, a functional separation is not possible because the subscription levels contain access to different communication channels and different ticket functions. During the administration and processing of tickets, it is not possible to check whether an agent has the access rights necessary for processing or not.
For example, is "Agent A" allowed to edit the Facebook ticket or only "Agent B"? What happens to the Facebook tickets if "Agent A" is the replacement for "Agent B"? Or will " Agent A" be able to see the customer-specific escalation times or customer objects, which usually only "Agent B" knows?
In our opinion, such a subdivision bears the risk of confusion for the agents and admins - and even worse: a probably worse support due to this.
At the other hand, the storage capacity is also tied to the subscription version, which is why a mix of several levels is not verifiable here either.