Pop!_OS should just be Ubuntu with some extras, so the equivalent Ubuntu version should be 19.04.
It should not be all that different from Ubuntu 18.04. I will try to follow your instructions exactly and see what happens.
The only reason I am trying to build from source is that Audacity 2.2.2 is what I get from the repository, and it is extremely cumbersome to use for heavy editing, as every time you do anything such as applying an effect, etc., takes the focus away from the current track (even if there is only one), and clicking on the track to get the focus back makes you lose the place where you were editing. I was hoping that this would be a bug (the same or similar to How to lock track focus?) that might have been resolved since 2.2.2.