You can use the Get-MsolUsercmdlet to generate a report that lists all the users who completed the Azure MFA registration process. The full command would look like this:
Get-MsolUser -All | Where-Object {$_.StrongAuthenticationMethods.Count -eq 0} | Select-Object -Property UserPrincipalName Reference:
https://docs.microsoft.com/en-us/azure/active-directory/authentication/howto-mfa-reporting

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Explanation:
Anti-phishing protection is part of Office 365 Advanced Threat Protection (ATP). To prevent phishing email messages from being delivered to your organization, you need to configure a threat management policy.
ATP anti-phishing is only available in Advanced Threat Protection (ATP). ATP is included in subscriptions, such as Microsoft 365 Enterprise, Microsoft 365 Business, Office 365 Enterprise E5, Office 365 Education A5, etc.
Reference:
https://docs.microsoft.com/en-us/office365/securitycompliance/set-up-anti-phishing-policies

Explanation

Group Writeback is enabled in the Azure AD Connect configuration so groups created in Azure Active Directory will be synchronized to the on-premise Active Directory. A security group created in Azure Active Directory will be synchronized to the on-premise Active Directory as a security group.
Device Writeback is enabled in the Azure AD Connect configuration so computers joined to the Azure Active Directory will be synchronized to the on-premise Active Directory. They will sync to the RegisteredDevices container in the on-premise Active Directory.
Reference:
https://docs.microsoft.com/en-us/azure/active-directory/hybrid/how-to-connect-device-writeback

Reference:
https://docs.microsoft.com/en-us/exchange/mailbox-migration/migrating-imap-mailboxes/migrate-g-suite-mailboxes

Explanation

If you added the contoso.com and east.contoso.com domains as custom domains in Microsoft 365, then the users would be assigned their user principle names as Microsoft 365 usernames.
However, the question does not state that you have added the domains as custom domains. Therefore, both users will use the default @fabrikam.onmicrosoft.com domain for their usernames.