Delta has a kitchen fawcet that you can control manually but it will
also toggle on and off by touching the metal part of the fawcet spout or
neck.

I'm wondering if it's possible to buy the electronics and the valve that
performs the touch-control separately (either from Delta or maybe
someone else makes such a kit) so that I can adapt it for operation on
another type of kitchen fawcet.

I know there are many motion-sensing fawcets, but I'm not interested in
that sort of control mechanism for a kitchen fawcet.