I finally got all this to work, using Z-Wave (as well as Zigbee, see above), and fulfilling all requirements in my original post, using the following:
(1) Aeotec Z-Stick Gen5, PC USB Z-Wave Adapter
(1) GoControl Z-Wave Dimmable LED Light Bulb, LB60Z-1
(2) Eaton RF9575DW Z-Wave Anyplace Battery Operated Switches
I used an Axial Controls HA Server on a PC with the Aeotec Z-Stick Gen5 PC USB Adapter for configuration of Associations (this is required only for configuration, not for continuing operation of the lights/switches).
I was unable to get the GoControl WA00Z-1 battery operated switches I bought initially to work reliably in a 3-way configuration with the bulb (I called their tech support but they were no help).
As stated above, I’m an electrician, and both the wireless Z-Wave and Philips Hue Zigbee solutions would often be cost advantageous in the 3-way configurations I describe, vs the traditional method of pulling wires to the switches in an existing house. The Z-Wave solution prices out at almost three times the Zigbee solution for this 3-way configuration, but there may be other advantages to Z-wave, and other configurations where Z-Wave would work better.