Unfortunately, it is not possible to transfer an existing site to another workspace. As a workaround, you can create a new site in a new workspace and transfer the ownership.
This is helpful if you were working on a site for a client using your own workspace and you want to transfer the site to the client's workspace.
- Create a new workspace for the client
- Import the site into the new workspace
- Bulk copy the Build and Environment variables from the original site to the new site
- Invite the clients as members of the new workspace
- Send an email to Gatsby support(scroll down and fill the form) to transfer the ownership of the workspace to the client.