It's unlikely these solar panels will contribute anything significant while indoors.
The spec sheet for the Powerfoyle cells show an efficiency of 2-3% at sunlight level brightness, even those figures would be ideal as being on the curve of the headset would mean uneven light distribution.
At anywhere from 150 to 360uA for the headset cell in typical indoor brightness, you might be adding 5% to battery life.
750mA with 80 hour life = 9.375mA
0.15-0.36/9.375 = 1.6-3.84%
Amazon review for the Los Angeles version shows it has a weak point which breaks and many users have a picture of their device breaking at that weak point. For a $200 USD headset. Buy a $50 one and use $150 for actual contribution to the environment.
Urbanista is advancing towards a truly cordless future. It has debuted the second-gen Phoenix true wireless earbuds and Los Angeles headphones. They bring a number of upgrades over their predecessors, and the good part is that they still rely on Exeger's Powerfoyle solar charging tech.