In FF15 the Astrals have bodies that can "die". But they are just sleeping.

"Sleeping Gods" is a recurrent thing in Final Fantasy. Even in FF8. Hyne created humans, and then went to sleep while they completed their task, literally moving a mountain.

In Type-0, summons cross over from a realm between life and death, which is why most powerful eidolons cost the summoner's life. But there's also a limited number of souls in the world, which is why they reset it.