From my understanding of it, Tantra is the holy union of the spiritual with the sexual. It is a meditation mindful of the thoughts, feelings, and sensations of sex. I find meditation apps very useful, and see how this might work.
All the tantric therapists I've been to have failed to deliver in this sense. The problem is that it is hard to meditate in this setting - if meditation means being mindful of the sensations without being lost in thought.
While this definition of tantric sex might be attainable, it'd be hard to find it with a WG. If you succeed, do let me know.