FWIW regarding ppa:freecad-maintainers/freecad-stable and ppa:freecad-maintainers/freecad-daily
My assessment of the status (at 16:30 EDT May 2, 2019) is that freecad ( 0.18.1+dfsg1~201904300243~ubuntu16.04.1 ) and freecad-daily ( 0.18~rc+git201903142046~ubuntu16.04.1 ) are working with python 2 on xenial.
Neither freecad-python3 nor libfreecad-python3-0.18 are available for xenial on either ppa, so freecad and freecad-daily with python 3 are not working.
The details are in the builds at https://travis-ci.org/pdgilbert/EgFreeCAD
, especial unfold the before_install sections. (If they don't unfold the result was empty.) Beware that the build site is a moving target, I am working on things.
As of a few hours ago, nothing was working on trusty. (There may be problems related to Travis' move 2 days ago to default xenial, see https://changelog.travis-ci.com/