This thread on Talk Cockatiels lists grapes as a safe food.
I'd stick with seedless grapes for your birds.

All fruits are high in sugar which is why they should be fed in moderation.

https://talkcockatiels.com/showthread.php?t=536

The list of safe foods for budgies is in the link below:

https://talkbudgies.com/diet-nutritio...s-budgies.html

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