Same problems after Sonoma upgrade.  A consistent hang at loading the company file.  

Called tech support and the technician wanted to see the system. Shared control, they saw the problem and then proceeded to tell me my system was all screwed up and that all my data files were corrupted.  They then wanted $3000 for a 6 month data management fee to fix the problem.  Yes, $3000.  That was the lowest tier.  There was a $4000 and $5000 dollar option.   My data files aren't corrupt but someone at Quickbooks tech support is.

I uninstalled the previous Mac Desktop Plus 2023 using CleanMyMac and reinstalled.  That allowed me to open the company file.   But as everyone else previously found, don't use the home or you will hang.  Not sure everything else still works.

What is incredibly wrong here is tech support knows this issue but are turning it into a giant "data management" fee scam.  Bad enough they weren't ready for Sonoma,  this may need a class action lawsuit if others are getting the whole "data management" fee scam thing.

Don't upgrade if you haven't already.