Thanks Dave. That helped us get it building -- it turns out we had set up virtualenv under pyenv instead of under system python. We also had to chmod+w on the pg_dump that is supposed to be re-written by install_name_tool.
Now we are just having issues running it. It shows the splash screen and then immediately exits with "pgAdmin 4 quit unexpectedly."
We tried looking at the Report..>Show Details, but it was just a dump of thread state. We tried setting qmake CONFIG+=debug, but we're not sure where the logs go. We looked in the running directory and in /var/log.
Any hints from here?