Hello, I found that you are looking for the developer to build the AWS API integration and subdomian.
First of all, we need to create new API in AWS lambda and integrate the proxy.
And to work with your domain, we can resubmit the request to your domain, so that the request and response can be exchanged.
Second, I found that you are looking for the subdomain. For that, I need to know that what service are you using for your web page?
If you use GoDaddy, we can create new sub domain in Domain Control Center.
Let's discuss your project in detail.
I will support you 100% I can.
Thank you.