From our knowledge there should be no problems with VNS and the stretchable band the Embrace watch comes with, as it does not contain any magnetic part.
The Embrace would be great to use alongside a VNS. VNS activates the parasympathetic branch of the autonomic nervous system. What we measure with the Embrace arises from the sympathetic branch of the autonomic nervous system. While the VNS can help reduce some kinds of stress, our device can help precisely pinpoint many other sources that activate a person's stress (which may be hard to pinpoint otherwise - e.g. they could be a smell, a fluorescent light that is sensed differently by one person than by another, etc.).
N.B. autonomic stress monitoring feature will not be available at the initial release of the app, it will be added in the future releases.