I feed my tiel mainly sprouts, mashed cooked veges( anything bird safe, more variety is better - kale/collard greens/peas/sweet potato/carrot/cauliflower/green beans/green peppers- I also add cooked quinoa grains), pellets(10-20%) and seeds and grains (20-50%), dehydrated veges as treats hidden in toys/foraging dishes(this isn’t necessary but is a healthy snack for them!) , and raw kale , broccoli and shredded carrot. You can feed boiled egg once a week if they are molting. Do not free feed sunflower seeds (2 per day advised max) , spinach ( high in oxalates- once a week is ok) , no junk food, no white bread , no potato(only sweet potato cooked), no celery stalks ( unless u remove stringy parts), chocolate + avocado is toxic, most fruit pits are toxic, strawberry and kiwi are safe with their very tiny seed, I don’t think grape seeds are safe so beware of seedless grapes that still have seeds. Feed fruit once every 2-3 days as high in sugar. You can offer healthy bird bread , unsalted popcorn once every 2-3 days as snacks .
Also be aware of Teflon pans( non stick pans with ptfe), food poisoning, metal toxicity( lead / zinc poisoning - costume jewelry) scented candles, popcorn machines, space heaters, hairdryers. Most of those listed have Teflon in them. Anything that smells bad might hurt them like paint fumes.