This can mean hosting static websites, applications on ECS, EKS, database, and Redis. Also it includes all the necessary underlying networking set up.
The rest of services are usually provided in their simplest possible form anyway.
On networking, you could set it up for them but would it be opinionated, ie your way only, or provide the flexibility of AWS and azure networking, vpc, gateways, transits and topology flex, and if not the client may feel constrained.
To better help you then I think you should draft up the service you intend to deliver and test if the market wants that, vs competitor offerings vs AWS scale. And I mean lofi don’t build, test the well defined proposition.
The service connects to your AWS account and builds stuff for you in your own account, if it makes sense.