I finally secured a “new” installer for QBDT for Mac 2019. It does install and successfully open on both macOS Ventura 13.6.3 (Intel powered MacBook) and Sonoma 14.3 (Apple Silicon Mac Studio). But, I still could not open any of my company files. Spent much of the day with QB Support via chat and phone. Sent them a copy of my company file for them to try opening. Expect results on Monday.