You can now attach EC2 interfaces to multiple different VPCs in AWS:

https://aws.amazon.com/about-aws/whats-new/2023/10/multi-vpc-eni-attachments/

The implications of this are pretty huge - previously to control access (with a firewall, etc) between VPCs you needed to use a Transit Gateway, generally associated with a centralized applicance via a Gateway load balancer.  This solution is great and scales very well, but its probably overkill for smaller environments.

What if you only have 2-4 VPCs?  This solution would work great - simple attach your NVA interfaces to different VPCs and modify your route tables accordingly.  This eliminates the cost and complexity of TGWs, keeping all the performance benefits.

What use cases can you see for this new functionality?  Off the top of my head, you could also provide remote access without using a VPN gateway too.  I’m sure there are more.

This also models correctly out of the box in Forward as well :)