polyurethane over oil based paint?

Hi everyone,

I am getting into some advanced projects and made a kitchen island out of maple which came out great. However, I used Maple and didn't know that Maple doesn't take dark stain very well.

I needed the piece to be dark brown so I am using Benjamin Moore oil based paint, called "bittersweet chocolate." It is a satin finish.
I am using a good brush for oil and high density foam roller.

I now want a little more shine than the satin and want to know if I can spray polyurethane on top of the paint?

I don't have spray equipment so will use the spray cans.

Also, I am not sure why some spots have less shine than others...is it because it is a dark color? If I spray on the poly will it even it out?

Thanks

Greg