How to Prefer a PPA’s packages over your distro’s

Some background

While was using Pop!_OS, I was trying to use this PPA for the latest point release of the Mesa drivers but apt was saying that Pop!_OS's repos are upstream and wouldn't let me upgrade. If I explicitly installed them and specified the PPA, the software center would later say I have an update and that it's going to install version 21.2 from Pop's repo

I needed to tell it to prefer the PPA repo over Pop's repo.

Solution

create a file in /etc/apt/preferences.d/ with something like this in it

Package: *
Pin: release o=LP-PPA-kisak-kisak-mesa
Pin-Priority: 2000

Pin-priority just has to be higher than Pop's pin-priority in /etc/apt/preferences.d/pop-default-settings.

In order to find what goes into Pin: release o=[here], use apt-cache policy and find your PPA, and copy whatever it has in o= and paste in your preferences file