Update: This script has been moved to the PowerShell Gallery.  All future updates will be posted here: https://www.powershellgallery.com/packages/Get-GALFromOutlook/

Export GAL from Outlook session. 
Specify output file for GAL export. 
2019-05-10 - Updated with additional GAL entry fields. 
           - Mapped 'PrimarySmtpAddress' to 'UserPrincipalName' so you can more 
               easily use the tool with http://aka.ms/pwncheck 
2019-02-13 - Update progress bar to show current/total objects. 
2019-02-12 - Initial release. 

Is it possible to export the GAL from Outlook if I don’t have access to a server?

Yes, yes it is.  Since we have the Power of Grayskul–err, PowerShell, at our disposal, we can manipulate Outlook to return this data to us.  All it takes is a little code.

This script will allow you to export basic information from the Outlook GAL as a sample.  For more infromation on additional properties available, see the corresponding blog at https://www.undocumented-features.com/2019/02/12/export-user-gal-entries-from-outlook/.