A (somewhat minor) breakthrough!
This morning I was trying to get Mia to eat. She was opening her mouth for Apple Jacks well enough, so that was an improvement. A few bites in, I asked her to take the spoon herself, and she did! She took a few spoonfuls by herself, which was nice. We hope this means she's getting her appetite back. She's eating a little bit more, but we have to keep making her feed herself. But it was good to see her actually eating something with a utensil. It's been a while.