Paint advice needed

Epoxy primer, then topcoat is the best choice. I like to use PPG DP epoxy, or Omni MP epoxy. You can reduce either a bit to make them spray out, and lay down easier.

Self etch primer is very misunderstood and often used incorrectly.
When a car body panel is sanded to bare metal, it is effectively somewhat polished. Same with brand new bare metal. So the factories use a phosphoric acid bath to etch the metal, so that the primer adheres to the metal well. This process was referred to as Bonderizing back in the day.
It used to be normal practice for body shops to use Metal Prep before spraying primers on bare metal. Metal Prep is a phosphoric solution that etches the metal. But this step was often overlooked and eventually got skipped altogether by many shops. However, it really is an important step. Self etch primers were developed to make it a simpler process. I'm old enough to remember using Dupont Corlar self etch primer, that had its catalyst in a glass bottle! Self etch primers contain a small amount of acid in them, which etches the metal a tiny amount. So on shiny bare metal, this is beneficial, but on old painted surfaces, it is pointless. Self etch primers should not be used on sandblasted metal. Sandblasted metal is rough, and somewhat porous on the surface, which provides lots of adhesion for the epoxy primer.
For best results and long lasting repairs, body filler should be used on top of epoxy primer, then sealed again with epoxy primer.
A top quality epoxy primer like SPI, DP or MP, is one of the key items to having a quality body and paint job, in fact, maybe even the most important.

Most body fillers are polyester based, and cannot be put over etch primers, or metal prepped steel, because the acid will react with the filler and cause major issues down the road.

Etch primer is really intended for bare metal spots only

So simply put, epoxy primer can be used over almost any clean surface, it adheres exceptionally well, and seals what is below. Single stage paint adheres very well to the epoxy primer.