I have a much smaller appetite than I used to, and I find myself fatigued if I eat too heavy of a meal. So, I plan for light meals and snacks during the day as I walk about NYC. What are some absolute must-eats in NYC for those on a budget?

I've already eaten at Katz' Deli, had a pretzel, hot dog (I think), and have had NYC pizza.

There are so many thousands of places to eat in NYC, our preference is #1 - something nearby. We've found in our several times a year trips to the City that a busy neighborhood to-go salad or bowl shop, small cafe, sandwich shop, noodles, sushi, or any number of other types of food we don't find in rural suburbia works for us. There are so many flavors we don't normally get to taste so trying something new if it strikes our eye is half the fun.

For some meals we'll even just stop in a grocery store and make a to-go salad topped with grilled chicken, or some sandwich fixings and enjoy a picnic in park, or even in our hotel room if we've had a very busy day.

Momofuku

So much as changed because of covid. In 2019, I liked Maison Kayser but it may now be Pain Quotidien:

https://frenchly.us/in-new-york-mais...ain-quotidien/

Good luck and please share where you found the right amount!

Though Pain Quotidian is a chain, my wife and I enjoy their offerings, soups, open face sandwiches, salads, etc. We find the food tasty and well done with a number of convenient locations in the city.

A dirty water hot dog, of course!

Another vote for Pain Quotidian, food deffo does not feel like a chain. And a good place to order a la carte to suit your appetite.I also like Pret a Manger for a quick and easy soup/salad/sandwich option, lots of locations in Manhattan though I think some are still temporarily closed. There are also so many hole in the wall places that you encounter as you stroll, sometimes with surprisingly good fare.

I prefer something from Gray’s or Papaya King to a dirty water dog anytime lol. The Halal Guys food cart is also pretty good.

I didn't realize Prune was closed. So many changes.

A few ideas -- Mamoun's Falafel (Greenwich Village and East Village).

Ess-a Bagel, Tal Bagel's or Bagel Bob's -- each has several locations in the city, each has various toppings to make a full breakfast or lunch.

Big Wong in Chinatown has a horrible name but good food. They serve the real thing and American style as well.

Xi'an Famous Foods -- hand-pulled noodles topped with cumin, lamb and chili, dumplings, etc. Several locations from the East Village to the Upper East Side.

Le Relais de Venise -- Steak and frites (and only steak and frites) $28.75 last time I looked. Wine by the glass. Good value.

As mentioned above, Gray's and Papaya have good hot dogs and the halal carts are pretty reliable. Try any of the food carts, for that matter. Our best pizza is not sold by the slice, but small pies are available, try John's on Bleeker or Lombardi's are great. Joe's on Carmine St has famous slices, but is well known and on the food tour circuit, so can be crowded.

You can find any ethnic food you like. Asian menus have smaller, lighter options.
Appetizers may be more than enough for you. Do you want to eat near where you are staying? Food likes, dislikes?

Forgot to mention Mighty Quinn (I think the city's best BBQ). Several locations.

The Meatball Shop -- varieties including vegetarian. Again, several locations.