Someone, somewhere may have a stock of exotic VFETs that are next to impossible to find.I do recall Sony's product line. From what I remember, VFETS were discontinued due to manufacturing costs as it did not take a hold in the industry.
The main idea was to replicate a vacuum tube amplifier as close as possible. In my opinion, while it was very close, repairing a blown up VFET amplifier was another story. Nightmares of having to find matched pairs and biasing issues were common. A headphone amplifier using a VFET is way an overkill.
Legendary Nelson Pass has an article about VFET, https://www.firstwatt.com/pdf/art_sony_vfet_40yr.pdf