I think the end portal frame should require an item found only in the end, so it's not as overpowered. Name tags should be craftable but they're not worth a nether star, especially only 3 tags.

Looks cool! IMO the elytra recipe would work better with Phantom Membranes instead of leather and string.

seriously you didn't even make the star craftable?

The only recipe I think is OP might be the Elytra one, because it removes the need to go to the end before acquiring wings.

I like the idea of renewable Elytra, but perhaps adding a material that forces you to hit the End Islands would add the balance back in. Such as Chorus Fruit, Purpur, or an End Rod?

Thematically, it might make sense to switch the Leather for Membranes, but that's just an opinion based statement.

Lovely Data Pack. I'm adding it to the psuedo-modded server world I'm making for my kids to explore. :)

End portals are unbreakable, so it would be wierd to have them as recipes, you can trap players permanently even sometimes. so it is kind of Op