Clearcoat over bare metal, whether rattlecan, wet clear using a spray gun, or clear powdercoat will inevitably result in spider thread corrosion under the clear eventually. Some folks think it's attractive.

Using boiled linseed oil like tired hands has done is an option, but requires repeated applications at regular intervals depending on the atmospheric environment where you live.

Another more permanent option used for over 100 years to prevent corrosion is having the frame and fork nickel plated by someone who knows what they're doing and will bake the frame after plating to prevent hydrogen embrittlement.

This example of a nickel plated frame is from the 1890s (link to image is firstflightbikes.com).