My primary concern with the Apple headset is the relatively low resolution of 23M pixels. Our eyes can perceive so much more detail, and I’m afraid the low resolution will reintroduce pixellation as is commonly seen on low end and curved displays.
The difference between a monitor and the lens of a headset. If you look at a 4K monitor up closely within a region of the screen of two inches in radius, you are not seeing 4K in that region. 4K of pixel applies to the whole monitor not to the eye's field of view as it does to a headset.
If you were using the headset as a monitor, you could zoom in on text and the text can effectively have infinite resolution as it scales up into view.
But you don't use your smartphone 1-2" from your eye.
QHD 32" works great, it's not quite two monitors but if you are using a tiling window manager or spend all your time in editor windows it's perfectly practical.
4k in VR is very different though, it's 4k per eye not 4k in dots per inch. 4k in VR will feel like a massive downgrade if you enjoy high DPI screens, but I think it should be usable. The state of the art is 12k I think and for people who like working in VR I see 8k on the pimax as the most common recommendation for good text rendering.