following up here if anyone else is curious about this:
while searching for more information on the hid "output report" structure of the dualsense controller, i stumbled upon a python library that implements all of this here: https://github.com/flok/pydualsense/blob/master/pydualsense/pydualsense.py#L445
based on that, i finally felt confident enough to give it a try with a short report that should only change the bytes for the big motors:
hidapitester --vidpid 054C:0CE6 -l 5 --open --send-output 2,255,87,80,160
... the last 2 bytes being the motor levels. aaaand ... it works! ![:) :)](http://forum.pdpatchrepo.info/plugins/nodebb-plugin-emoji-extended/images/grinning.png)
turning them off again via:
hidapitester --vidpid 054C:0CE6 -l 5 --open --send-output 2,255,87,0,0