Miscellaneous tools and services that may help

Synology Active Backup for Google Workspace

https://www.synology.com/en-global/dsm/feature/active_backup_google_workspace

This backs up all data (Drive, GMail, Calendar, Contacts) to NAS. Not sure if that can be used to restore to different accounts, yet.

Sign into Google with an alternate EMail address

https://support.google.com/accounts/answer/176347?hl=en&co=GENIE.Platform%3DAndroid#:~:text=When%20you%20create%20a%20Google,%2C%20get%20notifications%2C%20and%20more

EMail forwarding services

https://improvmx.com/