Confluence export from Cloud to migrate to Server does not allow to specify a project

We experience a major issue when trying to export a specific Confluence project/space which should be imported to the Confluence servers of a customer.

When trying to export something, we can only get an export of everything from the cloud. No certain project/space can be selected.

We need a quick solution (or workaround) to export only a certain project/space to afterwards import it into the customers' server.

The same applies to the corresponding Jira project.