How to design batteryless circuits with power harvesting
Here is my guess regarding power harvesting: If you would make the power harvesting antenna reasonably large and have it always right next to a WiFi accesspoint or next to any other transmitter and these are operating 24/7 then yes, it can probably be done.

But for any practical application that you could place anywhere so not near to anything transmitting radio waves all the time: NO, there will not be enough energy available to do anything usefull.

You, like many others, are grossly overestimating how much energy you can "harvest" in a practical scenario. You also may want to have a look at this video.