GotoFinal
There is a lot of suggested features like https://vrchat.canny.io/feature-requests/p/more-trackers-for-fullbody-tracking or to support various not too popular devices like leap motion and other ones.
I can fully understand that supporting all of that in vrchat would be hard to maintain, so I want to propose different solution.
Instead vrchat could provide a special API on PC, that could be used to provide tracking data from other sources for any selected humanoid bones (and maybe extra stuff in future)
Community could then provide such api modules themself, without any additional work needed from vrchat.
(implementation example would be to just load .dll file from some directory and it should then implement some standard method returning a simple data structure with all tracking data)
Vrchat already uses networked IK, so data about skeleton is already sent over the network, so it should be possible to just allow people to send more points instead of calculating them, without adding any additional load on other people.