If you want the most productivity on the go, nothing beats a laptop with good resolutions that runs linux and the i3 windows manager (and no, nothing on Mac comes close). Once you get used to i3 commands, you won't need a second display.
For AR/XR, wait till someone releases a pair of glasses with a tiny low res monochrome text based Micro Oled display, with an open source interface.
If I need to work (coding in this person's case) on the go, a high quality laptop with good screen resolution is superior to a headset. Using a constrained headset that's optimized for consumption strikes me as similar to using an iPad for coding (or other serious work). It can be done and there are even example of people doing amazing things, but those are exceptions.
Typing and screen mirroring is so delayed that it's unusable.