hey @brunont,
Currently, there isnt a way to transfer projects.
Since your app is already published to the Google/Apple stores, the easiest approach is to transfer the entire expo account (ie) give the company access to your expo account.
If you don’t want to do this, then you need to create a new expo account for the client company, publish their expo project under that account (existing standalone apps will not receive updates since it’s from another developer), then download your distribution certificate and push notification certificate from apple’s developer center, and reupload those credentials when running exp build:ios with the new account.