How can I replace Fedora with Ubuntu without using a USB drive?

I have Fedora installed and I want to replace it with Ubuntu without using a USB drive. I want to use Ubuntu because of less software availability on Red Hat.

Booting ISO from GRUB Menu

The method on this page should work for booting an Ubuntu ISO from the Fedora GRUB bootloader 20.04 booting .iso from GRUB menu No need for a USB here.

To reiterate:

• Add the following menuentry to /etc/grub.d/40_custom:

  menuentry "isoname ISO" {
    set root=(hdX,Y)
    set isofile="/[path]/[isoname].iso"
        loopback loop $isofile
        linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile toram --
        initrd (loop)/casper/initrd
  }
  

Where (hdX,Y) is the disk and partition the ISO is on, [path] is the path to the folder the ISO file is in, and [isoname] is the name of the ISO

• In Terminal run:

  sudo update-grub
  

• Reboot and select Ubuntu from the grub menu. Install as usual.

• Please let us know how this works for you.