Long ago I gloss clear powder-coated some polished engine covers on a motorcycle project. Came out great and lasted a long time. I also did some contrasting aluminum pieces that were glass bead blasted and then powder coated clear. In the gloss clear the blasted parts looked like a metallic silver paint so we redid them in a mat clear powder coat and they looked fantastic. In mat finish they looked like sand cast parts. Wish I had some pictures to show, but it was from before digital photos were a thing.
The powder coat adheres well to the part if it's prepped properly, it's very scratch and ding resistant, and keeps moisture out. Clear coat paint will eventually allow moisture to creep under or through scratches and then natural corrosion happens under the paint.