You could use a very strong magnet from the other side of the windshield. It ain't iron but nickel is still a ferromagnetic metal.
That's what I'd do. Use a coat hanger, with about a 1" 90 degree bend on the end. The curve of the nickel will allow the bent end to slide under the nickel and allow you to pull it up and out. That is is of you haven't already gotten it out with the popsicle stick and tape. My concern there is the stick may be too thick to allow it to slide over top the nickel. But who knows.
My concern on this is, even being careful with a wire or other metal tool of any kind, the possibility of scratching the dash. I bet Randy is as particular about minor details on his hot rod as I am on mine.
Just have the windshield removed by a professional. Get the nickel, clean the area and reinstall the windshield.
pencil eraser. or rubber glove with a popsicle stick/shim inside. should give you enough 'tack' without scratching or leaving residue.
There are always many ways to go about it, I think everyone covered them, I recommended what always works for me, as an automotive technician for 30 years, these are request by customers that are pretty much freebies, ive tried every way that does not work also, every situation is different. of course the coins in you 1700$ navigation radio from your kids, will cost a pretty penny.
If you could put the car on jacks high enough to get even a slight incline leaning away from the corner, and use a random orbital sander on the dash (no sandpaper!) you may be able to vibrate it out.
I'd like to know more specifics about the vehicle, make/model/year/engine, how long you've owned it, etc. etc.
I was unsure. I posted a magnet. I guess I don’t quite get how the metal detecting works when wheats are found etc. I would hate to scratch it but the stick and tape makes sense. Won’t scratch.