Porneia is not derived from pornos, which is merely the masculine form of the feminine noun for prostitute, porneia. The feminine form is much more commonly used, for obvious reasons, since in the ancient, as well as modern world, female prostitutes greatly outnumbered male ones.
I am not a Greek scholar, but I think it highly unlikely that the modern word fornication derives ultimately from pornos rather than porneia, the much more common noun form.
The word “prostitute” (female) is “porne”. “Porneia” refers to all such activities engaged in by both “professions”, and adultery (forbidden in the Ten Commandments) is very much included.
I seriously doubt that throughout the Roman and Greek Empires there was a shortage of male prostitutes, or even a disproportionate ratio of female to male. Consider their culture, especially the Greek one (heavily into pederasty).