"Moreover, we were able to significantly increase the maximum output current (≈ 205 nA) by connecting 30 wood sponges in parallel to each other, making a demo

"Moreover, we were able to significantly increase the maximum output current (≈ 205 nA) by connecting 30 wood sponges in parallel to each other, making a demonstrator suitable for wooden tables or floors." which is at 0.69V so to get 1A, you will need 150000 (though I doubt it would scale like that) all being stepped on actively. So as a power source? seems unlikely. As a sensor, sure.