Thank you for your quick reply!
I don’t know exactly how, but I have sound back! I’m running Lubuntu 20.10 on a very old (Win Vista era) PC. I thought I would give Wine a try and I installed the latest Wine Staging and although it didn’t display any video because the iGPU is so old it’s not supported by Vulkan, it played sounds. So I go back to the native Ubuntu version and suddenly there’s sound. I’m thinking maybe I was missing libs or something. Anyway, thanks.
P.S. Try to reuse an old Mac and put Ubuntu on it for testing for you can.