We need to migrate some devices to an open_balena that we use for testing, as they are R&D devices

Reading the suggestions on the forum, we came to the conclusion that the configizer: GitHub - balena-os/configizer: Safe(r) balenaOS config.json updates remotely would be the best solution for migrating devices remotely, however we did not find in the documentation how to make it change the variables of the server (dns, vpn…), the variables necessary for a safe migration. So we would like to know how to use this project to carry out this migration?