Note that the Apple SIM isn't new, nor tied to the release of the new iPad model today. It's been around since at least 2014. I remember going to an Apple Store back then to pick one up. The associate at first didn't know what I was talking about but eventually found them somewhere stashed in the back-office.
It seems we’re just waiting on carriers to catch up to the idea at the moment.
https://www.androidcentral.com/using-project-fi-pixel-2s-esi...
https://www.theverge.com/2017/10/4/16424740/google-pixel-2-x...
This used to be true but it doesn't save you money now to buy an iPhone attached to a carrier plan. Apple will even sell you a carrier-free iPhone [1]. I would love an Apple SIM for travel to Canada, etc.
> (e)Handset locking prohibited. No licensee may disable features on handsets it provides to customers, to the extent such features are compliant with the licensee's standards pursuant to paragraph (b)of this section, nor configure handsets it provides to prohibit use of such handsets on other providers' networks.
Maybe in the U.S. Much less so over here.