By 'most of the hard sciences', you seem to have chosen a sliver of one of the hard sciences, which plenty of people in that science think is just smoke and mirrors. If a 'general audience abstract' is a good idea, it shouldn't be balked at because of a single theoretical field which is quite controversial. Let other journals handle those papers :)

Unless string theory all of a sudden gained everyday applications i think i would aim for fields like biology, chemistry and similar first.

Yes, biology makes the most sense, as thats usually what gets "translated" to clickbait style headlines like "Quinoa cures cancer".

This week i read a headline that could be interpreted as saying green tea would prevent zika infections.

In reality it was a chemical of some sort found in green tea (and elsewhere) that seemed to counteract zika. But it required concentrations that you would never find in nature.