It doesn't have enough magnetic material to work well as a magnet holding surface. And it doesn't have enough chalk-writing material to work as a chalkboard.

In the places where it makes sense to have magnet boards, use sheet steel (cookie sheets, oil drip pans, flashing ... whatever) in a frame.

You could try painting these - after priming - with commercial chalkboard paint. With pure metal behind them,m they would be way better than iron powder mixed into paint.

dry erase boards!