Hiding an etched surface on porcelain enamel
It’s not that common for porcelain enamel to become etched, somebody put a strong chemical on the washer top at one point, I guess if you don’t want to try the clearcoat on your washer top, you could experiment by getting an old lid or top off a machine that has porcelain on it and etch with some muriatic acid and then see if you can hide the damage.
The clearcoat will only hide the damage the surface will always be etched underneath.
No, you do not want to powder coat over porcelain enamel. It would look OK but it’s not the same as a porcelain finish. It might be a good idea if the overall finish was really bad shape.
John