I’d like to add that Nuke and Natron are VFX Compositing software and are not primarily meant for tracking…
The way you do 3D tracking in Nuke aids you in 3D Compositing and set extensions, etc.
There are a few plugins that were made for Nuke (https://www.keentools.io/) which enable you to do facial motion capture, but I’ve not used them.
For something like this, I’d really suggest using a software that was made for this sole purpose, like PFTrack, Syntheyes, etc. If you can’t afford any of these, Blender, as I already mentioned, is the best option you can use.