Comment 57 for bug 1779827

You don't need to install all of the updates from the -proposed repository, only the kernel. When you check the proposed box in the software updater, you are effectively adding the following line to /etc/apt/sources.list (mirror is whatever mirror you have chosen):

deb http://mirrors.namecheap.com/ubuntu/ bionic-proposed universe restricted multiverse main

You can then either use the software updater or apt to install the kernel. I used the following apt command on the command line:

 apt-get install linux-generic

This command automatically pulled in the other dependencies such as the kernel headers and modules from the -proposed repository.