Here is a link to a non-surgical, less invasive way to treat bumblefoot.
https://www.tillysnest.com/2015/12/non-surgical-bumblefoot-treatment.html/?spref=pi
I have used it on small lesions with success.
I was chicken sitting and discovered one of the hens had scabs on the top as well as bottom. The top plug that came out easily after soaking, the bottom one was rather recalcitrant.
Even if you resort to "invasive surgery", a good soak is a good start. Gets the feet clean!