Yeah, they are porcelain enamel. Mine looks like brand new. Unless you somehow burned off the coating, it should come clean. It almost looks like you did burn it off. Do you have any barkeepers friend handy? That stuff cleans up porcelain enamel like new.
Yeah, it must be a pretty rough surface under the coating, but looks like you got it cleaned up darn nice.
This is a big reason I like it so much, you can use independently from the removable grate section Like you show it here. I’ve done egg scrambles, fajitas, veggies and taters etc and have been pleased. Hope you get a lot of enjoyment out of it!