Dynamics portal migration to new subscription

Hello,

For a customer, I am trying to correctly migrate a Dynamics portal from one customer (subscription) to another

I already found the CRM Configuration Migration tool to migrate data from portals entities, which I managed to make work

https://community.dynamics.com/crm/b/crmpowerobjects/archive/2018/08/27/microsoft-dynamics-365-crm-configuration-migration-tool

However, I am stuck later, when I set up the new portal (indeed it deploys a new architecture does not take into account the data that I just imported)

Is there any other tool for doing this? what is the correct procedure to follow to complete a complete and "clean" migration of the portal?

Are there also other tools to make backups of this portal?

Looking forward to your help!