TL;DR
The sub-module interface which configures the BGP Peer does not expose/configure the ability to configure import/export policies
export_policies - (Optional, Beta) routers.list of export policies applied to this peer, in the order they must be evaluated. The name must correspond to an existing policy that has ROUTE_POLICY_TYPE_EXPORT type.
import_policies - (Optional, Beta) routers.list of import policies applied to this peer, in the order they must be evaluated. The name must correspond to an existing policy that has ROUTE_POLICY_TYPE_IMPORT type.
Add the above settings to the interface sub-module and bubble up to the interconnect_attachment module to allow the assignment of import/export policies
Terraform Resources
* google_compute_router_peer - https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/compute_router_peer
Detailed design
Additional information
No response