There are two installers. If you have the small stub installer, definitely try the full/offline installer. It is available from:

https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

Does that work any better?

Tried every installed I can find. Even finished regression attempts. save failure. Installer either can't find something or can't remove something to run setup.exe

What do you mean by "regression attempts"?

Have you done a normal shutdown and restart of Windows since the uninstall? In case there are some problematic file locks.

Firefox installers use 7-zip technology. Some enterprise environments have an issue with this, but usually personal system do not, unless your security software is very unusual.

previous releases. 102, 104, etc. Unzip works fine. Haven't had any issues prior to the latest 105, yet that updated on my other machines. Can the install be run on a command line with a log file option of some sort? I assume somewhere there's a version that does just that.

And yes, I restarted mores times than I'd like to count.