how does one run the installer without booting from the installer media?
in Windows, the setup.exe can do that. in linux, i find it difficult as a disabled to do so.
The installer is not designed to run from the installed system as far as I know.
It may be asked to delete the disk it is runing from for example.
If you have disabled USB devices in the EFI BIOS and that is stopping you then why not enable USB devices long enough to do the install and then disable them again?