On paper headsets like MeganeX are on the same ballpark [0], while Bigscreen beyond for instance offer a completely different proposition (ultra light) for only slightly lower resolution [1]

[0] https://en.shiftall.net/products/meganex8k

https://store.bigscreenvr.com/products/bigscreen-beyond-2

>is it still really the only headset with twin 4K resolution

There are quite a few others, even some with near or at 4k res per eye released before the Apple product. Even just the Pimax 8k being the world's first dual native 4k headset early 2019.

The problem with alternative sets is, as always, a software/ecosystem one which for gaming Valve helped massively by getting everyone onto one platform (SteamVR). It's tough to do similar with Apple as they lock everything down for "security" with the added benefit of preventing competitors from creating competing products. They're happy to interoperate with Wifi and Bluetooth standards etc, though (before someone claims that doing what they want with their platform is Apple's choice - the same people who grin when MS got hammered for anti-competition with IE Windows bundling, something Apple regularly escapes).

Shiftall Meganex 8K is out, and Pimax Dream Air is upcoming. But those are PCVR headsets, not... whatever the AVP is.