In Blender, mocap is a split workflow consisting of 3d tracking, solving and then linking that tracking data to armatures or other objects. Blender isn’t built primarily for mocap. It’s just a great FOSS option out there if you cannot afford any commercial software or plugins.
Also Natron doesn’t have a true 3D workspace yet so even if someone manages to make such a node, either in the form of a PyPlug (Gizmos for Natron) or a complete plugin like the ones from keentools.io I mentioned in one of my previous replies, it won’t work.
Also with development at a halt, there is no way we’re getting a true 3d workspace anytime soon.
So If you have a very specific requirement, i.e. multiple angle support, etc. better to go for software that you know can fulfill your requirements.
Blender can utilize multiple camera angles for tracking and facial mocap, but it’s a very twisted workflow. I think there might be some mocap plugins out there for blender but I’ve not heard of any prominent ones.
So the best you can do is search for any other free software that can do what you need to do, or get specialized commercial software.