The turkey hoagie is a Philadelphia sandwich, and in Philadelphia the dress is not optional and not a garnish. A turkey hoagie ordered the right way arrives with shredded lettuce, tomato, raw onion, oregano, hot or sweet peppers, and a pour of oil, and that list is doing the work the meat cannot. Sliced turkey breast is the blandest thing the hoagie shop slices: lean, mild, barely salted next to the capicola and salami in the case. The defining fact of the turkey hoagie is that it leans entirely on the hoagie's dressing system to season a meat that brings almost nothing of its own.
The craft is in the roll and the dress working together. The Philadelphia hoagie roll has a crust with enough structure to hold a long, oil-slicked load without buckling and an interior tender enough not to fight a soft filling. The turkey is shingled the length of it, often with provolone laid against it so the cheese supplies the fat and salt the meat lacks. The oil and oregano are not condiments dropped on at the end; they lubricate and season the interior so the dry, lean turkey reads as juicy from the first bite to the last. The raw onion and the peppers carry the acid and the sharp top note. The tomato is the moisture risk and goes in as part of the dressed structure rather than a wet afterthought, because a flooded crumb fails a foot of sandwich in the middle. Built correctly, a turkey hoagie eaten cold holds together end to end and tastes seasoned rather than plain, which is the entire test the dress exists to pass.
The variations stay inside the hoagie's logic and change the register. A turkey-and-provolone build adds the cheese as a deliberate richness; an oil-free mayonnaise build trades the Philadelphia dress for the softer deli reading; a turkey club hoagie braces the roll with bacon and a third texture. The same long roll wears other cities' names as the hero, the grinder, and the wedge, small dressing and bread differences that locals defend. Each of those is a codified build with its own rules, and each deserves its own article rather than being crowded in here.