First, I totally agree the pumpkin guts, seeds and all, are safe for your chickens. If you still have babies the seeds may be too big but even adult bantams as small as seramas should enjoy them. I split excess cucumbers, summer squash, and winter squash for mine. They eat everything except the stem and sometimes skin.
Don’t count on the seeds as a wormer. That’s been studied by a couple of universities, they were looking for an organic way to control worms. They were studying goats, not chickens, but the basics are the same. The seeds do contain a substance that can paralyze roundworms but the dosage varies a lot from one pumpkin to another, even the same variety of pumpkin. It’s unlikely the chickens are going to eat enough seeds to make a difference with worms, they just won’t get enough of that substance. But they are still a great snack, they will not hurt.
What did people say were unsafe about grape seeds? There is a lot of misinformation that shows up on this forum, I’d like to have an opportunity to address whatever they said. Mine love grapes, seedless or seeded. They make a great snack.