A Reddit post lead me down the right path. For me the solution was on Windows 11:
Uninstall all Gigabyte software
Restart in Safe Mode and uninstall nvidia driver with DDU (critical to do this step)
Boot into normal Windows once more and install the nVidia driver from Software Update (for me this installed a 400’s version nVidia driver)
Install Gigabyte Control Center
Boom, it finally shows up with RGB Fusion tab as well as shows up in SignalRGB (though it sucks in SignalRGB, it’s controlled as one RGB vs an ARGB strip)
Download from nVidia their newest driver (for me, v554) and install, continues to function correctly.