The Philly-style chicken sandwich is what happens when the cheesesteak's method travels without its hometown. Strip the build to its grammar and the cheesesteak is not really about beef at all: it is about thin protein chopped on a hot flat-top and bound with cheese melted into it rather than onto it. Run sliced chicken through that exact method and you get this sandwich, which exists less as a Philadelphia order than as the country's shorthand for griddled-chicken-and-cheese-in-the-cheesesteak-manner. The defining thing is that the technique survived the trip even where the bread, the cheese politics, and the steak shop did not. On a national menu it is the chicken sandwich that is fried by no one and griddled by everyone.
The craft is in adapting a method built for fatty beef to a lean bird. Ribeye carries enough fat to stay tender when chopped hard and fast; chicken does not, so the protein is sliced thin and worked quickly on the steel and pulled the moment it sets, because a few seconds too long turns it dry and stringy in a way beef forgives. The cheese still goes on while the meat is on the heat so the two become one mass instead of a layer on a layer, and the choice runs the familiar range of American, provolone, and the processed sauce, though the milder chicken often invites the sharper cheese to give the sandwich a spine. Griddled onions and frying peppers do the same work they do on the beef version, supplying the sweetness and acid a lean protein needs to read as balanced. The roll has the same demand it always has, soft enough to compress to the filling and structured enough to carry a hot, cheesy, greased load without folding.
The cheesesteak family branches at exactly this kind of single decision, and the chicken builds keep the method while changing one variable apiece. Adding marinara and mozzarella pushes it toward the pizza form; adding long hots makes it a pepper build; serving it on a split soft pretzel changes the carrier entirely. The buffalo-and-blue-cheese chicken cheesesteak is a hotter cousin running the wing's logic through the same griddle. Those deserve their own articles rather than being crowded in here.