On machine with Win 10 I run Dell OS Recovery Tool and switch to "extended recovery mode",
in the middle panel I put path to ubuntu-20.04.4-desktop-amd64.iso file and tap Next...Next to write
on USB stick.
I run ubuntu-install from thats USB drive in UEFI and install it normally, reboot, go to the BIOS, switch boot to UEFI
(I see ubuntu option in UEFI:), save and exit BIOS and...