How to successfully create bootable backup of working Breath install?

[Corgi]

Forgive me if this is a question with a very obvious answer, but I've been working on this for some time and can't seem to crack it.

I've been trying to create a full disk clone of my functioning Breath install so I have a backup to restore to in the likely event I goof something up. I use my chromebook daily and it took me quite some time to get it set up as I like it (and many esoteric commands I would have trouble finding again) so I'd really rather not have to start from scratch.

I've tried both Clonezilla and dd, and while they seem to work to clone the Chromebook drive to my USB stick, I am never able to successfully boot from them. The most common stall point is I'll try to boot from USB at the ChromeOS boot selection (where you hit ctrl+d to boot from disk) and it just makes a loud horrible beep.

I'm not sure if this has something to do with the boot drives, i.e., if the Chromebook boot drive fundamentally does not work when cloned to a USB. I'd appreciate any help or even just a link walking me through the right steps to follow to get a working backup from a Chromebook Ubuntu install.

[runcros]

Just to clarify , when you boot to an usb, you need to do ctrl+u
Maybe here you can have some tracks.

[Corgi]

Just to clarify , when you boot to an usb, you need to do ctrl+u Maybe here you can have some tracks.

Thank you, yes, to clarify I do use ctrl+u to try and boot from the USB but I still receive the beep error. I am pretty sure I have been on that very stackexchange page looking for solutions, haha.

I've successfully used dd and Clonezilla, and I think even gnome-disks to create backups to USB (using a vanilla Breath live USB to access them), and they all seem to succeed, but the resultant USB drive always refuses to boot.

[runcros]

Can you compare partition from a working usb and a non working usb ? Maybe there a difference of partitioning that cause an issue