Choosing any cloud platform completely depends on the user's needs. So there are different types of migrations also done by professionals. Google Workspace to Office 365 migration is also one of them that most users look for. Both are popular cloud platforms for managing different types of data like emails, contacts, calendars, meetings, etc.

Two manual methods exist to transfer mailboxes from Office 365 to Google Workspace account.

Method 1: To manually migrate from Office 365 to Google Workspace, follow these steps:

Prepare: Create user accounts in Google Workspace and assign licenses.
Export Data:
Use Outlook to export emails to a PST file.
Export contacts as CSV from Outlook.
Export calendar events as ICS files.
Import Data:
Use Google Workspace Migration for Microsoft Outlook (GWMMO) to import emails from PST.
Import contacts via Google Contacts using the CSV file.
Import calendar events into Google Calendar using the ICS file.
Verify: Ensure all data is accessible and provide user training on Google Workspace.

Method 2: This is also an official method to switch Office 365 mailbox to Google Workspace account.

You can read it here: https://www.mailsdaddy.com/blogs/migrate-microsoft-office-365-to-google-workspace/