A number of our customers want to leverage VMware Cloud on AWS to expand into a new market. As the VMC SDDC can be deployed in a matter of hours, it allows customers to enter a new market without having to commit CAPEX.
A side benefit of using VMC for this use case is that, if the market expansion were to fail, customers can exit the market as fast as they entered it (they are not left with racks of hardware).
If on the other hand, the expansion is successful, customers can easily scale up and increase the size of their infrastructure in minutes.

Architecture
In this scenario, there is no need to stretch network as new applications are to be built. Therefore using NSX L2VPN or HCX L2VPN is not needed and I would recommend customers leverage a simple L3 VPN instead.
If possible, prefer the route-based VPN option (vs policy-based) and build two for resilience.
Check out the following blog for more details on L3VPN:
https://nicovibert.com/2018/12/14/l3-vpn/
From a management perspective, connect the new Cloud vCenter and the existing on-prem vCenter in Hybrid Linked Mode for unified management.