Company letterhead / templates in Word Online

I've spent some time getting our company's Word templates available on Mac and Windows. We can also create a new Word document using our letterhead template through a SharePoint doc library.  Where I'm now stuck is making these letterhead templates available through the Word Online portal here https://www.office.com/launch/word    

It's possible I'm looking for any update to this question posted in July 2019 https://answers.microsoft.com/en-us/msoffice/forum/all/setting-company-templates-for-word-online/47dfb350-bcd2-4890-bbc3-9e180df01768

Any other suggestions to provide access to letterhead templates for our users through the Word Online portal?