There shouldn't be any problems using an Embrace alongside a VNS as Embrace does not contain any magnetic parts. The VNS would actually be great to use alongside Embrace, because it activates the parasympathetic branch of the autonomic nervous system. Embrace measures electrodermal activity which is a common measure of autonomic nervous system activity.
If you are using a VNS, we recommend you wear Embrace with the stretchable band. If instead, you'd like to use the Vegan Leather Band, we suggest consulting it with your doctor because it contains magnetic parts.