Never used any sealants over the past 15 years of ownership.
Just weekly washing, with a quick 30 second polish inside and out every month.
Even though they may still "look" shiny after a month or two of just washing, the polishing little but often just keeps them smooth and shiny with minimal effort meaning never needing hard scrubbing or wire wool.
I suppose any of the popular metal polishes would work for light duties.
I've had good results with Autosol and Megs Metal Polysh like this.