I tend to rotate through the same few things:
Avocado toast (easy enough to make at the office if you take in some English muffins or whatever your choice of toastable carb is, a ripe avocado, feta and a seasoning blend)
One of the Asian style bagged salad kits, supplanted with frozen dumplings.
A different frozen salad kit supplemented with some rotisserie chicken.
A homemade chicken salad (I have several recipes I rotate between) using a rotisserie chicken.
A homemade tuna salad.
And leftovers.
I would say that probably ~45 weeks of the year I am having one of, or some combination of these for lunch.