What is the best way to migrate a multi-TB MySQL database from on-prem to gcloud Cloud SQL?

I have several multi-TB on-prem MySQL databases I need to migrate into Google Cloud's managed MySQL offering, Cloud SQL. I have migrated two of size ~1TB so far with mysqldump but this method is far too slow for the bigger databases. Ideally I would like to use Percona Xtrabackup but I don't know if it is possible? Has anyone completed such a migration? What tools did you use? Thanks in advance