My go-tos are lettuce wraps and cheese tortillas!
Lettuce wraps - big lettuce leaf with good stuff in it (I usually put taco-seasoned mince, chopped peppers, cheese and sour cream in mine).
Cheese tortillas - big thinnish slice of Edam wrapped round some ham!
Halloumi sandwiches - use halloumi slices instead of bread
Insalata caprese - sliced mozarella, sliced tomatoes, olive oil and maybe a bit of pesto.
Or you can use my slob lunch idea - chop up some chorizo, cover with grated cheese and then pop it in the microwave for a bit so the cheese melts.
Don't forget, low-carb dinner leftovers are also a good option. And if you want to splash out, there's various places online where you can buy tortillas with <5g of carbs...which are also great for when you're making Mexican food at home.