The short answer
Yes — pumpkin is safe, and the seeds are a bonus.
Why
Pumpkin flesh is rich in vitamin A, and the seeds are safe too — many budgies love them, though they're a little fatty. Cook the flesh until soft.
How to feed it
Offer cooked, cooled flesh, or a few raw or dried pumpkin seeds as a treat.
How much & how often
A small serving a few times a week.