So, here's the story:
I created a Live USB drive and booted with it on my new (UEFI) DELL laptop.
I installed Ubuntu on a second USB drive (full installation on a USB drive, not on the internal drive).
During installation, I told it to place GRUB on its own usb drive. What Ubuntu actually did though, was to install the main grub on the usb drive, however, it also added an EFI bootable option for Ubuntu, that "linked" to grub found on the USB drive whenever the laptop was booting. I was unhappy that it did that, because I didn't tell it to touch my EFI, but it did (there's no option during installation to tell it to not do that).
So Ubuntu now boots on the laptop by the EFI booting option, that "links" to grub found on the usb drive.
Now I'm sending that laptop back though and I'm getting a refund (because the N3060 CPU proved to be too slow), and I'm left with a USB Ubuntu that I want to be able to boot on any other UEFI laptop (just so I don't have to redo the installation again).
How do I convert that semi-bootable USB drive into fully bootable USB drive (like the one found on the Live CD, which is able to boot directly from USB on any laptop, and without the need for an EFI entry in the BIOS)? I tried booting you see on my other laptop with it, and it just doesn't boot (can't find grub, I'm guessing, there is no error message, just a blinking cursor).
So I want to convert that USB installation of ubuntu, that relied on EFI to link to grub, into something similar to the Live USB that is able to boot anywhere without any EFI entry! Is there ANY way to do this?