Would it be possible to use electromagnets on the outside surface of the ISS to stay anchored to it or is it made with non-ferromagnetic materials?
Because each of the aluminum-can shaped components of the Station has to be lifted into orbit, minimizing weight is crucial. Lightweight aluminum, rather than steel, comprises most of the outer shell for the modules.
Let's see if there are any advantages to using magnetic grapples instead of the current system.
Those magnetic grapples would have to be electromagnets. Permanent magnets strong enough to prevent an astronaut from flying away would be very hard to remove.
So instead of passive elements (two short cables and carabiners), you'd need a power source, electric cables and switches, and two magnets, plus a backup (two short cables and carabiners) in case you have a power failure. So you'd add several kg worth of equipment, plus two more cables to get tangled in.
On the plus side, you'd be able to place the magnet anywhere on the hull (if you made the entire outer hull/Whipple shield out of steel), and you'd save a few seconds because you don't have to manipulate a carabiner through those really thick gloves.
Magnetic grapple points could be quite useful. They would not be as failure resistant as caribiners so they would likely only be used for anchoring tools and equipment, not crew.
A small patch of magnetic stainless would likely wight less than a carabiner eye-bolt. Or existing eye bolts could be made of magnetic SS.
The magnet would not need to be an electromagnet. In precision machining, instruments are routinely held in position by permanent magnet mounts. The magnetic field of the mount is engaged or disengaged mechanicaly. They are easier to reposition than Velcro.