I'll take my own food
Luckily Jetstar seem to allow that.
Get on board | Jetstar
I know Air Asia "do not allow" you to bring your own food. Of course people do and also of course the same flights attendants who do nothing when passengers leap out of their seats at the bay before the belt sign goes off also do nothing about people bringing their own food.
AskAirAsia - Can I bring my own food on board?
Tiger says no...
https://www.tigerair.com/au/en/faqs.php