Apple internal iOS devices used by engineers are "dev-fused". This hardware configuration opens up the device to some extent, allowing Apple engineers more latitude when developing software.

There have been articles saying that Apple lets some third party security people use these devices.

E.G. https://macdailynews.com/2019/08/06/apple-hands-hackers-secr...

I can see how giving that access that might make sense, but I don't know if that article is true.

Dev-fused devices would also be very useful to Apple adversaries like NSO in developing hacks so I would actually expect Apple to continue to keep tight control over them.