This is a gear puller
You put the prongs around the back of the wheel and the threaded center rod on the middle of the helm bolt (center of the wheel) then wind the end with a shifter until it "pops".
You can also get 4 pronged pullers.
I'd soak it in WD40/Inox overnight, partly screw the nut back on say 3/4. If you can get a good swing with a hammer strike the nut hard and pull the wheel left/right as you hit the nut. If you can't get a good swing you could try using a socket smaller then the nut on a socket extension then hit the end of the extension.
It will take a good wack.