Yes. It is finally clean. (Cue heavenly chorus.)
When I was cleaning the drip pans from my stove, I remembered that I had read a comment somewhere in the middle of my many cookie sheet cleaning tips that had mentioned using ammonia to clean out her oven. My oven, oddly enough, is not very dirty. I gave it a wipe down with a wet sponge (no other chemicals) and it got most of what was in there cleaned out. I couldn’t remember if the commenter decided to stick her cookie sheet in her oven with ammonia, but decided it was worth a go.
I put my cookie sheet in the cold oven on the bottom rack, put some ammonia in a bowl on the top rack, and let it sit overnight.
Here is what it looked like before (after my 11 different ways to try and get it clean):
And here is what it looks like now:
Clean! Hooray! That used some steel wool and elbow grease too after I took it from the oven, but I had tried steel wool over and over again with many different products and I couldn’t get it all off. The ammonia worked great. It also took off some of the oil splatters on the glass on the inside of the oven that I couldn’t get off earlier with just the wet sponge.