Trail

The last link is useful. There are two directions from here:

MYBOTSHOP/mbs_unitree_ros has gone 404. They have converted the repository into private. The repository was public at least till Feb 2021.
MYBOTSHOP forked unitree_ros 3 years ago. They probably carried out their development inside mbs_unitree_ros
They’re now selling the code: Quadruped Robotics.de with a dedicated forum and also a Userguide for ROS and A1
But the internet never forgets. I found their older code repository on one of the distributor networks. This is up for further testing now.

His repository YushuTechUnitreeGo1 is legendary. He ripped the Go1 robot apart and penetrated any backdoor in the robot that you could possibly imagine.
The README contains all that you need to know. The most relevant takeaway for me is that Unitree Go1 uses MIT Cheetah software code. So I will be looking deeper into that code.
There’s some pretty tarnishing information about Unitree Robotics in his notes. The TL;DR is that Unitree used and sold MIT Cheetah hardware and code without attribution till they were called out by hackers like him.