Have you tried starting Catalina in Safe Mode?
Start up your Mac in safe mode https://support.apple.com/guide/mac-help/mh21245/10.15/mac/10.15
Apple: "Safe mode may help you resolve or isolate problems that you’re having with your Mac.I did some thought. I imagined my system opening in safe mode.
How can safe mode matter?
Added this to my list of attempts to fix. Right now, going for a new installation of Catalina on a different disk, so the old one will still be around.Apple: "Safe mode may help you resolve or isolate problems that you’re having with your Mac.
When you start up in safe mode, your Mac prevents some software, such as startup items, from loading, and it performs a check of your startup disk. Your Mac may take longer to start up because of the check."