Followed latest guide with Bulldozer 15h recommendations as is and installed Catalina 10.15.7 without any issues,
only problem I had was USB flash installer wasn't booting with constant
AppleUSBHostPort::disconnect: persistent enumeration failures
So I figured it out to be because actual drive USB flash drive is 3.0, used an old 32gb Toshiba USB-2.0 drive and everything worked fine
Actual GPU I have is an old Radeon R9 285 which is actually supported by Catalina out of the box so I didn't had to do any extra GPU spoofing or any other thing.
System runs stable, hadn't tested USB ports yet throughoutly but Audio works fine via VoodooHDA
only problem I had was USB flash installer wasn't booting with constant
AppleUSBHostPort::disconnect: persistent enumeration failures
So I figured it out to be because actual drive USB flash drive is 3.0, used an old 32gb Toshiba USB-2.0 drive and everything worked fine
Actual GPU I have is an old Radeon R9 285 which is actually supported by Catalina out of the box so I didn't had to do any extra GPU spoofing or any other thing.
System runs stable, hadn't tested USB ports yet throughoutly but Audio works fine via VoodooHDA