I do not see Sharepoint 2019 on the planned list for BE20.4 Beta testing.
You may want to register or contact the email address in this post:
had some information from Veritas that they thought SharePoint was dead for on premise.
They totally missed the on premise product, there 'might' be have a GRT solution in BE 20.4 beta.
I was told by Veritas 'One step at a time. :)'
Now they are trying to get SharePoint 2016 GRT to work.
Even Microsoft Server Active Directory 2019 is not supported.
And they call this day 1 support for Windows 2019...