I’m using the polygon tool, setting my color to White, but it auto-fills the polygon when I’m done. I’d like the interior of the polygon to stay transparent. Is this possible?
Not with that tool, no. Instead, you can use the Polygonal Lasso tool (one of the selection tools) and create your shape that way, and then
Stroke it to create the outline.
Would be nice to have an outline option though, since the Polygon Tool has a nicer preview for this kind of work ):