Perform surgery only if you're SURE it's bumblefoot.
If it's not bumblefoot (there would be a black scab), I suggest treating for an injured leg.
The best way to do that is to build a chicken sling ~~>
https://www.backyardchickens.com/t/609764/my-chicken-sling
You can make one using items you already have at your house.

Just make sure she has water and food within reach. I would sprinkle some turmeric (reduces inflammation) in her food and offer some high-protein treats (like boiled egg or meal worms) to get her eating.
Is she still eating and drinking normally? If she goes off food and water, please let us know.
If you can get her off her leg for a while, the swelling may go down and allow her to heal herself without constantly using her leg.
And to answer your question about the surgery.... Chickens are not mammals and handle/exhibit pain very differently. A bumblefoot surgery is performed without anesthetic. Place a towel over her head to make it dark, and she should calm right down. Then you perform the surgery, get the kernel out, and pack the wound with Neosporin.
Again, without a black scab or puncture, I am unsure if bumblefoot surgery would help. Obviously, finding the source of the suspected injury would be great.
Keep us posted!
MrsB