Hi
Does your business account on google is still in good standing ?
I ask as you can migrate to O365 with Microsoft wizard, as seen here; Migrate consumer Google Workspace (formerly G Suite) mailboxes to Microsoft 365 or Office 365, need a valid account on both side.
If your account on google is not in good standing, I would think that you might have to do a manual migration. AKA; Create your O365 tenant, create the mailbox and modify the MX. After that your userbase will receive email, but you will have to import them to O365 the old way. That step we need to know what mail client you are using. (as like importing the pst inside their new mailbox in example if you are using office)