Hello there, @Aussiebron.
Thanks for joining this conversation. Allow me to chime in and share some information about the compatibility of Excel 2019 to QuickBooks Desktop (QBDT).
At this time, we don't have an exact time line as to when the Excel 2019 will be compatible with QBDT. But QuickBooks is constantly updating, rest assured that we will notify you through an email blast or next release. I'll also update you in this post once we get the update as well.
In the meantime, you can always check out the article provided by my colleague above for additional information about the QBDT system requirements.
This should answer your concern for today. Please mention me in the comment section if you have any other questions or if I can be of additional assistance. Have a wonderful day.