What a cognitive dissonant coincidence, I was talking with a friend about doing exactly this† just a few hours ago, to drive some passive speaker he has lying around, in all sorts of interesting ways.

† (not with a router, mind you, but a Raspberry Pi or similar)

If your interested in using a Raspberry Pi as a guitar pedal, there is this project https://shop.electrosmash.com/product/pedal-pi-kit/

There is NeuralPi as well: https://github.com/GuitarML/NeuralPi

Am I reading it wrong or does it miss the actual "pedal" part? I was expecting something like measuring changes of strength of wifi signal from another device caused by moving his leg closer or further from the router to turn the effect on or off; but this is completely underwhelming, it could be run on pretty much any other system with linux.

I assumed the author would have been using the ADSL modem for sound processing, but is only using the CPU. Still neat.

Mmm ok but hear me out… A behringer delay is $20

You've already paid for the crappy router you've shoved in a drawer somewhere.