I have been told that QB in Sonoma might work, and might not work.

QB support will tell you that it doesn't work. If you trust them, you should follow their advice. Unfortunately I don't believe them. There are indeed a small issue when running QBD 2020 on Sonoma. You can ask Fiat Lux for advice but I noticed you don't trust them either. Maybe you should consider switching to QBO as suggested by Support.