@dosdude1's method for installing Catalina worked fine with 10.15.2, however upon upgrading to 10.15.3 I found that integrated audio has gone away entirely. I can only use an external USB audio adapter now.
Is anyone familiar with this issue and how to resolve it?
Sadly after a repatch of 10.15.3 with the boot USB the audio has still not returned @dosdude1. I then tried a "Legacy Audio Patch" after that and still no success with audio that had worked in 10.15.2.