This is my thoughts, @TwoCrows may have a different opinion.Her crop was not fully empty this morning and after reading the links posted here I'm almost sure she has pendulous crop. She has been like this for almost 2 years now and she does gorge. I can purchase the acidfied copper sulfate tomorrow so I will start there and then she might need the bra. I was thinking maybe the bra with a change of diet for a short period of time less feed and just adding some organ meats. I could be completely wrong here but just from my own experience as a human organ meats are nutrient dense without the effect of distending the gut like grains but of course hens are not the same. Just thinking she would need less food with the nutrient density being so much higher.
Any thoughts.................maybe an experiment for a few weeks with a very small amount of fermented grains............thanks,
Of course over the years I have had hens expire which is not easy but I always like to try. I actually had a hen recently that I was sure passed. I brought her in the house and then one day she just flapped her wings, rolled over on her side feet up in the air gasped and closed her eyes. She wasn't completely gone but almost there. I decided to pick her up and put her in my lap until she passed but she sat there and somehow managed to stay alive. I immediately gave her antibiotics and the next 3 days were touch and go and you could hear her coughing and gasping for breath but she made it so always good to try.
Try the acidified copper sulfate along with the instructions in her article on treating a slow crop (https://www.backyardchickens.com/a/impacted-slow-and-sour-crops-prevention-and-treatments)
Feed her normal poultry feed wet. A drastic change in diet could make things worse.
Once you see how she responds to treatment and help from a crop bra, then slowly change her diet if this is what you want to do when she gets better. Organ meat is a fine way to add extra protein to the diet, this may eventually help her feel more satisfied, but as a sole source of nutrition it would not be practical. Poultry feeds are nutritionally balanced, so adding meat(s) would be in addition to her normal feed. Some other things to give when she is better would be hard boiled eggs, tuna, mackerel, sardines and fresh leafy greens (kale, mustard, etc.). Fruit like apple or grapes are a favorite for mine as well. Making sure she has a source of grit would be essential as well. Some chicken keepers let their birds find the grit in the soil which is fine, but I prefer to make purchased poultry grit (crushed granite) available free choice as well.
Again, you may be right that she may eat less when extra protein is introduced. I feed an 20% protein Flock Raiser formula, they don't seem to eat as much feed as what I see reported that chickens on layer feed (16%) eat. But I haven't really sat down and "crunched the numbers" on food consumption. I do give other things (fruits/veggies, etc.) most days as well.
There is no harm in trying to correct this. She does seem to be in good spirits

I hope you see improvement soon, please keep us posted and thank you for the wonderful videos, they help alot!