Healthy Toddler Snack Help!

Best way to get him to snack on those things is to keep giving them to him and let him know "Nothing else. This is it." thats what I tell my almost two year old, "you don't want it? OK, then all done" and I start to remove it and she changes her mind & take it or goes about her business, she will come back to it when she is hungry and when offered again she eats it! lol sounds simple does'nt it? He's too young to decide what he likes and does not like, they are eating to live, that is something that we as adults sometimes have to re-learn...also if he sees you eating it he will eat it, it took me two previous kids to learn they will eat what you give them just be consistant! I'm assuming he is an only child at the moment. My daughter will eat anything she sees her siblings eat.
For the dining experience try a small table setting for snacks, like child size picnic table or table and chair set at this age they like to feel like they are in control and a high chair and booster seat feel confining to them.

I'm confused. He's 18 months old - is he pushing you around, demanding fruit?

Thinly sliced, steamed carrots (kind of sweet tasting for kids)

Steamed zucchini

Veggie pizza diced up

I would get a salad & let my son have some WITH me. It seemed appealing since it was MINE. I would put everything on it!

Green beans (they are soft)

Yogurt? Not a veggie but something different.

If you do put him in a chair, limit the time to about 10 mins so he does not
associate the chair with "stuck in it forever".

Also, when I was going through a trying time w/my toddler when he wouldn't eat, I would take him out to eat. Somewhere inexpensive. For some reason, being out of the house in a different venue would make him more apt to experiment.

My ped advised me to sneak frozen spinach into the spaghetti sauce. It
kind of worked.

Yogurt or go-gurt if you want something that travels well. Both my son's(now 3 and 5) love snacks and go-gurts can be frozen and then eaten or thawed and eaten.
Cheese
Crackers
Nutri-grain bars the soft ones, good for on the go too

I would keep trying what you are already trying. Research shows that it takes 12-16 exposures to a new food item until a toddler will readily accept it. He will likely eat many of the veggies you have tried if you stick with it. Also - steamed carrots (or raw), broccoli, cauliflower florettes, hard boiled eggs. The general feeling among nutritionists is that ADDED sugars are a problem - naturally occurring fruit sugars are not. So there is no reason to limit his fruit intake.

String cheese, yogurt, fruit, crackers.....

My son always liked a plate to "pick" like crackers, cheese, peperoni, fruit, veggies & dip, raisins, etc. He's always been a BIG fan of variety.....

As far as the 'not messy' part have you seen that cool bowl that can twirl all around and not spill? They sell them everywhere, I have seen them on TV, at Walmart and Target. They are orange and turquoise I think? That would be a good idea to eliminate the mess...

My kids' favorites were:
Hard Boiled Egg
String cheese
Cheerios
Kix
Go-gurt (my kids like it frozen)
Grape/Cherry tomatos
Green beans-steamed
Cauliflower-steamed
Broccoli-steamed (call them trees, he will love it)
Olives
Granola
Wheat Toast lightly buttered
Sliced or cubed Salami, Turkey or Ham

~Somehow my love for vegetables has rubbed off on all 3 of my kids, they will eat ALL of them (except green peppers which I don't blame them for I do not like them either) my 'trick' with veggies I have labeled as 'steamed' was to sprinkle them lightly w/rice vinegar..my kids love them like that (definitely try the fresh yellow, orange & red peppers this way, they are SO good) and will even eat canned spinach w/apple cider vinegar?!

My DD is going through this too and it is frustrating! I recommend those slim round breads spread with hummus. Let him dip all the veggies you mentioned in hummus too. Smash black beans, top with avocado and cheese on top of a tortilla for a quick bean burrito. Tom Thumb grocery store sells jicama sticks in the produce section, she likes those. Chopped tomato and avocado. Greek yogurt mixed with frozen fruit. The other thing I have discovered is that when DD wont eat anything, if she has a little fork or a little spoon then she will eat more food. Good luck!

My son is a big eater too - he just turned 3 and is sorta slowing down now. So one thing is that I would try to really make sure there is enough protein in my son's breakfast. It was sorta my only hope that he may stop wanting snacks for a bit. Anyway, healthy snacks:
I do veggies in muffins (have to find a healthy recipe) I use one where the base in bran flakes cereal and then grate in carrot and a few raisins.
Also a really easy one is pancakes. I use a whole wheat pancake mix and then when its in the pan I just grate in carrot or zuchinni. My son didn't notice that trick until he was over 2 and he didn't care, just ate it anyway, cause it's yummy. Those freeze really well too if you make a whole batch.
Beans - canned beans. I know you mentioned chick peas I'd recommend "pink beans" they are quite soft and don't have that feeling of a shell that other beans have. I literally open a can rinse them off and hand them to my son. They keep in the fridge for several days.
Hummus is a good one too with pita or steamed carrots, crackers etc.
Avacado is really good. Instead of giving your son just plain fruit mix it in with half of a mashed avacado. Super healthy and yummy. (oops - messy though)
Good luck!

Have you tried making kale chips? I just made a batch and my 2 year old ate half of them.