I’ve tried offering veg to both my tiel and to the Quaker, and man oh man - You’d think I’d insulted their mother the way they react to it
It takes time and different ways an ideas of offering.
Things that helped mine. Offering in in chunks spread out on a shallow dish so each type wasn't touching. And offering out side of cage for them to explore on their own. But I would also mix it up and offer shredded veggies. Or I would steam a mince and mix with quinoa or a little cooked pasta preferably ehole west pasta or chicken pea or lentil pasta.
Another thing that helped. Kinda like mentioned above. I hand out treats by hand a lot. Then I hand a pea or single piece of corn or tiny apple fragments. Stuff in general well liked by parrots. I hand out pellets too. They have gotten used to me handing them food treats so are willing to try the new stuff. The more different textures or things they try the better and better they get at trying new stuff and foods. But only offer dont chase them with it if they aren't interested I just drop it on the plate for them to investigate on their own.
I would set them up on the breakfast bar with a plate if salad stuff and sit and eat my own salad with them. Any human food I make that is safe for them I offer . O offer while I'm chopping, I offer while I'm cooking.
I hang stuff with bird skewer at their head height.
Parrots love to find stuff and destroy by nature. Let them find big hunks of veggies to destroy. It does lead to eating.
Parrots can really love and enjoy veggies. They love being curious about foods. It's so enriching for them as well as healthy. But it can be something that needs to be taught that this stuff is food. Birds learn best by watching their flock. So that's you, start Grubbing on veggies, share, or pretend to keep it away. Keep trying !