On AWS, how do I give access to my subcontractor to create and manage his resources only?

I am about to start a cooperation with a 3rd party (subcontractor). He wants me to provide him with a development environment (cloud infrastructure). Later on similar infrastructure will be needed for a production environment.

I would like to give the subcontractor full access to EC2 instances that he creates and no access to others. Furthermore he will probably need access to some other services like Elastic Container Services (ECS).

Right now I have a full AWS account with User accounts for my developers.

Is it possible to create a policy for my subcontractor so that he could freely create and manage EC2 instances, but only those which he created? Similarly for ECS?

One other option that I see is to create an entirely new AWS account and create a sub-account for my subcontractor with admin privileges. This way I could separate his work from my own.

What would you suggest?