I don’t think it is correct that this solution is applicable for you. The solution described here is for a Librem 5 that effectively can no longer boot i.e. you can’t even login to the phone.
So if you switch off all three Hardware Kill Switches and boot up, do you get the login screen (PIN pad for entering your PIN)? If you get the login screen and you can login then this topic is not for you.
If this topic is not for you then building uuu and building Jumpdrive would be a lengthy digression. Building uuu is not necessary in more recent versions of Ubuntu anyway i.e. not necessary for Ubuntu version at or after 21.04.