Milk carries about 1 gram of protein per ounce, and a grande latte is mostly steamed milk — hence 11–13 grams with dairy, depending on fat level. Espresso itself contributes well under a gram.
Plant milks change the picture: soy keeps roughly 10 grams per grande latte, oat typically 3–4, almond 2–3, coconut 1–2. If a latte is doing duty as a light breakfast, that difference matters more than the calorie difference.
Practical pairing: dairy or soy when you want the drink to hold you until lunch; almond or oat when the drink is alongside food and protein is coming from elsewhere anyway.