VTK virtual reality works really well, including direct volume rendering of 4D data sets (e.g., beating heart), so it is a good solution for professional applications and full-quality data sets. However, I agree that it is a major inconvenience that you need to use a gaming laptop (which is heavy, hot, and has abysmal battery life) or a desktop PC (large and not portable). For mass deployment, classroom use, etc. quality and performance is not the highest priority and computational power of the standalone headsets suffice (and these devices are cheap and portable).
We keep pushing top-quality virtual reality for professional use (medical training and surgical planning), but we are also involved in creating content (such as https://www.openanatomy.org/) that would be suitable for inexpensive virtual reality visualization for education and patient communication.
What kind of data sets do you work with? What viewing features do you have in mind?
There seems to be tons of javascript 3D viewers that supports virtual reality, too. You can export the scene to glTF and load it into these viewers. Have you tried them? How do they compare to capabilities of vtk.js?