Mostly those products are made of machine cleaned bones left over from producing chicken meat, the remaining meat is mechanically separated from the bones, and some products are used to bind the mulch together and pressed in meat like forms adding salt and other ingredients to give it some taste.
( as pipefitter welder I worked in the food industry as well, so some hands on experience here....)
You really did expect real chicken in the sandwich? tut tut tut....;)