Galvanized dryer drums
I would agree with Dan. It’s not worth the effort, it’s very hard to paint over galvanize metal and have the paint stick. There are special products that allow you to do it but they’re pretty chemical laden primers.
I use some of these years ago to paint, galvanize, rain, gutters, and things on my house so that you could actually have paint stick to the galvanized metal and it worked but I don’t think I’d want that stuff inside my dryer.
Plus the galvanized drum as it is it’s just fine if you want to restore an older dryer with one, just use it as it is.
John L