The procedure in the link you provided takes seconds, BUT the re-install of the OS takes about 45-60 minutes. I may even consider going back to MOJAVE since CATALINA does not recognize a dozen 3rd-party apps I like to use (i.e. I get the icon with the slash through it showing that it will not function with the most recent OS).
It is times like you are going through that a good bootable external clone is so good to have around. One of those things you hope you never have to use but if they are ever needed they are invaluable.
As to those dozen third party apps, if they haven't been upgraded to 64 bit — which is what makes the broken — they are almost certainly no longer supported and they are overdue for replacement. Murphy's law and McGillicuddy's corollary still hold true.
They will fail and at the worst possible time. Long experience indicates it is time to let them go and move on.
