I did a full install of the latest Ubuntu desktop to a USB stick using the instructions at How to Create a Full Install of Ubuntu 20.04 to USB Device Step by Step and it boots fine
However, if I download and install the latest kernel from say https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.13-rc7/, grub2 still boots v5.11.0-18
I'm doing this because I need some new drivers. Do I need to copy boot files again as in the original install? Or is there something else like this image is unsigned and therefore doesn't even show up in grub's advanced menu even though update-grub saw all the kernel images?
Thanks