To find this out, you need to do a deep dive of ingredients yourself. What you’re asking would be a seriously onerous task for any of us.

Make your own food so you can control what goes in it.

Pretty much everything in my home, from fried chicken to stir-fry.

Low FODMAP at fast foods includes reduced wheat and high fructose corn syrup https://www.fodmapeveryday.com/low-fodmap-fast-food-options/

Spaghetti sauce is one thing I can think of. It doesn’t necessarily have to have onions in it, but it can.

A quick search came up with…

The KFC 11 Spices recipe found by Joe Ledington reads as follows:

Mix with 2 cups white flour

2⁄3 tablespoon salt
1⁄2 tablespoon thyme
1⁄2 tablespoon basil
1⁄3 tablespoon oregano
1 tablespoon celery salt
1 tablespoon black pepper
1 tablespoon dry mustard
4 tablespoons paprika
2 tablespoons garlic salt
1 tablespoon ground ginger
3 tablespoons white pepper

NEVER having to personally deal with IBS, I might be wrong. I had a boss who suffered greatly from it. He didn’t have to go as far as to watch the spices in his food. He just had to be extremely careful to the fresh things in his food. He could eat foods with onion powder/salt or garlic powder/salt, but could NOT eat fresh onion chopped up in his food nor fresh garlic added to his food. He definitely could NOT eat onion rings nor blooming onions. Assuming that the above recipe is anywhere near correct, the little bit of garlic salt probably won’t be enough to stop you from eating your KFC. In the beginning, you will need to rely on a lot of trial & error to determine what upsets your system. If your IBS is so bad that you can/t handle even a small amount of spices, you probably should STOP ordering meals & having them delivered & start making your own meals so you know EXACTLY what is going in them!!! That way YOU have total control over what you eat. While my boss was in the trial & error phase, they discovered that tomatoes were one of the things that set him off. His doctor said that he didn’t know of any patient who couldn’t eat tomatoes, but took them off his diet. The doctor had started with the usual culprits & worked his way into anything else that might be part of the problem for my boss. You may need to ask the places where you normally order from if their food contains ingredients that you aren’t supposed to eat. Now, the kids at KFC probably won’t know what ingredients are in their secret spices as #1 it’s a secret & #2 they work with a premixed jar of spices & don’t know themselves what’s in it. My boss also discovered that greasy foods set off his IBS, so KFC could cause a flareup but not because a little bit of garlic salt, but because it’s fried. My boss decided that rather than cutting out ALL spices & foods that he’d go the trial & error route. Once he ate something & it caused a flareup, he’d put that on his list of DO NOT EAT ever again!!! You might also find that black pepper isn’t your friend!!!

Article below with list of foods to avoid. Also advice for seeing a dietician.

‘Meet with a registered dietician if you are considering this diet. It’s important to make sure your eating plan is safe and healthy. He or she will have you eliminate FODMAPs from your diet. Then you gradually add the carbohydrates back in one at a time and monitor your symptoms. A food diary and symptom chart may be helpful tools.

Harvard Medical School

I would avoid meat loaf. (For one…)

Q: Which foods have onion and or garlic in them?
A: My favorites.

Spaghetti sauce, guacamole, stir fry vegetables, omelets.

Hey RDG..

I’m with Dutch.

Buy a couple onions. Maybe a Vidalia, and a white onion.
Garlic cloves, or just the powder would be easy to get.

Off the top of my head? An easy thing for a guy like me, would be something baked, or pan fried in margarine not grease…

You can usually find some chicken strips in a freezer section, raw. You could thaw them. Wash them. Put them in a oven safe Pyrex container with margarine (or butter,) and simply throw some chopped up onions in with some chopped/minced garlic. Might be nice to buy some marinade that garlic and onions would compliment well.
Combine in Pyrex. Cook for suggested time on chicken bag.
Serve over rice, or with potatoes.
I would personally add some green pepper, and maybe some tomatoes, or mushrooms. Depending on what marinade you get.

As we know, I’m not a doctor. However. I feel like I should mention that lots of onions can cause heartburn, or other gastrointestinal issues. Being as you’re already having stomach issues…

It might be nice to drink some ginger ale, or ginger beer. Ginger is great for helping a tummy feel good. Especially if it’s carbonated…

As a poor person, most of my adult life, I’ve learned a ton of cheap things to eat.

Baking is a cheap and easy way to feed yourself a decent meal. Stay away from drive-thru type foods.
I used to buy a couple turkey legs, for less than $4. A can of Campbell’s condensed soup, of your liking. Combine in a Pyrex bowl, bake, and enjoy. Cans of sliced potatoes and beans are cheap. There’s your side…

Dark meat (poultry,) is usually pretty cheap. Canned vegetables too.
I survived five years, eating a different type of canned beans everyday for one meal. And one “bigger/more expensive” meal per day. Just add a couple bottles of OJ, or a few V8 type beverages, to keep from being malnourished…

You can add onions and garlic to all that stuff.

I used to cook a mean Ramen noodle stew. 3 packages of your preferred Ramen (like $1.) Put on a pot of water, or again Campbell’s condensed soup, with water (aprox $1.)
When pot starts to boil, drop 3 raw eggs in. (again, pretty cheap.)
Add cheese, garlic, onions, peppers, or whatever.

Bring off boil and stir slowly until it forms a mush-like substance. Bam! You can eat half the pot, put the pot in the fridge. Take it out later, and put it straight back on the stove top, with maybe a bit more water. Bring to quick boil. Bam! Another meal…

On super poor days. You can ball up some pieces of cheap sliced bread, and heat up a can of beans…. A cheap loaf of bread, and can of beans can feed big guys like you and I for $3—$4/day RDG…( I know you’re financially challenged, like me.)..

It’s not luxurious. But. That would be boring…Right….

Good luck with your cooking buddy. When you perfect cooking on a ridiculous budget, it kinda feels like you aren’t scrapping by… And. It impresses the ladies!..
Got me a good girlfriend for about a year once, by dazzling her with peanut butter sandwiches, and Ramen stew!