TL;DR: magnetic nanoparticles are for the use of magnets in cell transfection, nothing else. Using them for mRNA vaccines makes no sense as nobody is being asked to go through a gigantic magnet afterwards, are they?
If the vaccines were magnetic, there would surely be plenty of pictures of the vials sticking to magnets (though I'm guessing the cap may very well be steel). Though it's BS just on the face of it anyway as is the 5G stuff.