The 99.9% availability configuration requires two connections in a GCP single region. For more information, see the configuration for Dedicated Interconnect or Partner Interconnect:
Topology for Non-critical Applications Overview
For non-critical applications that can tolerate some downtime, Google recommends that you build the topology for 99.9% availability. To be covered under the non-critical applications SLA (99.9% monthly uptime percentage), you must build your network according to this topology.