Does Max Number of B208 Limit the number of B308's that can be used?
Or,
Does Max Number of B308s Limit the number of B208 's that can be used?
No.
The maximum number of B208 modules and B308 modules that are available to the panel type can be connected at one time.
The only limit would be available power and SDI2 cable distance specifications which are detailed in the module documentation as well as the panel Installation and System Reference Guide (ISRG).