Standalone mode and deploying to multiple environments across 2 subscriptions

[PbALpi7xEX]

Curious to know if this is possible or recommended... some best practices say to break down directory structure by environment and component with different state backends. Reduces blast radius, keeps state files small. But increased complexity in workflow to plan/apply proper sequence, not to mention shared dependencies between states, and some code duplication.

Is the terraform caf module meant to be used to manage all resources within an environment? Or can it be used in a multi environment/component structure like mentioned above, simply by feeding it a different set of data in tfvars?

If so, how would you access state data in other state files? For example, ip restriction in app service to allow traffic from app gateway subnet only?