Utilizing existing light switch for new GFCI outlet

We are updating our master bathroom. Currently, we have a GFCI outlet which we are not going to change and a double light switch which controls a ceiling light and a light bar on the wall above the mirror. We will no longer use the light bar above the mirror but only the ceiling fixture. That will free up a light switch which we like to use for a second GFCI outlet. Is this possible to do. If so, what would the wiring scheme look like?

We looked at GFCI outlets today and noticed that they have 2 silver screws and 2 brass screws for wires….do we use all four screws?

Many thanks to all.