George E. Cawthon wrote:

...watts = 0.4 x volts x amps, for some undercounter fluorescents.

Do fluorescent lights have a power factor?

Sure... 0.4 in the case above.

But, that said, if the undercounter light fixture say 15W, then that
is how much is used regardless of power factor

Yes.

and w=va still applies. or am I wrong...

You am wrong. W = PFxVxA.

Nick