Yeah iOS supports BLE Coded PHY since the iPhone 12 / iOS 14. The tricky part is negotiating it at the library level. flutter_blue_plus doesn't fully expose Coded PHY yet so I'd need to handle it through platform channels on both sides. It's on my list though, the range improvement would be significant!
Oh, I thought that support was only present in some iOS 13 beta and then disappeared again? (At the OS/driver level; I’m pretty sure the hardware supports it.)
You're right, I was wrong about iOS 17 auto-negotiating Coded PHY. After digging deeper, Apple did support it briefly in iOS 13.4 betas but pulled it in iOS 14 and it hasn't returned. CoreBluetooth still doesn't expose PHY selection at all. The iPhone hardware supports it but the OS won't use it. So BLE Long Range is going to be Android-only for now. I've updated the roadmap to reflect that.