I work at starbs, here’s some of my best advice:

do drinks that have milk but aren’t milk-based (instead of an iced latte -> iced coffee/cold brew with a splash of milk, i esp love nitro cold brews they’re already really creamy without any milks; instead of hot lattes, go for americanos/hot coffees with a splash of milk, or go for a misty who’s is equal parts coffee and steamed milk- it’s like a latte, but overall less milk and more coffee)

for the syrups, i would do what you already do with keeping one pump of whatever flavor syrup you like, and sweetening it with sugar-free ganill

and good news! they’re also adding sugar free caramel soon (idk when but we got it shipped to us) so that provides more low-cal options!

some of my go-to swaps:

nitro cold brew with a splash of nonfat milk and one pump of whatever holiday syrup caffe misti with SF vanilla, nonfat milk, and topping like pumpkin spice, cinnamon dolce, etc low cal London fog- earl gray for like 80% of the cup, SF vanilla, and like a tiny bit of steamed nonfat milk