Wifi is already microwaves
«802.11 (b/g/n) typically operates on the 2.4 GHz band. This is conveniently the same/very close to the band that your microwave oven emits.»
https://www.howtogeek.com/171869/why-does-running-my-microwave-kill-my-wi-fi-connectivity/
Yes, bad for brain. DNA. Who cares about infertility and cancer? In practical terms: not many