The Bullet 2.86 has improved Python bindings, pybullet, for robotics, machine learning and VR, see the pybullet quickstart guide.
Furthermore, the PGS LCP constraint solver has a new option to terminate as soon as the residual (error) is below a specified tolerance (instead of terminating after a fixed number of iterations). There is preliminary support to load some MuJoCo MJCF xml files (see data/mjcf), and haptic experiments with a VR glove. Get the latest release from github here.