Daws

To be sure the right manifest is selected, you can check OpenXR developements tools UWP app:

https://www.microsoft.com/en-us/p/openxr-developer-tools-for-windows-mixed-reality/9n5cvvl23qbt?activetab=pivot:overviewtab

Probably you've already installed in your system.

It's usefull to see if the runtime is correclty up and running, there's also a simple 3d scene for testing.

The "system status" panel give you a detailed info about the selected runtime.

Pay attention as it's from Microsoft it warn you about the Mixed Reality is not selected, you  can ignore it.

I found how to run Minecraft Bedrock in OpenXR using a Rift headset, or probably many other.

Now MC use OpenXR as default runtime.
The choice of the runtime is made system wise by a register key, that point to a manifest where is writed which runtime to use.

SteamVR, WMR and Oculus has its own manifest. And probably if you're unable to run MC in VR is because you've the wrong manifest registered.

So you need to write the path of the oculus openxr manifest modifying this register key, in case of Oculus:

[HKEY_LOCAL_MACHINE\SOFTWARE\Khronos\OpenXR\1]

"ActiveRuntime"="c:\Program Files\Oculus\Support\oculus-runtime\oculus_openxr_64.json"

This is considering you've installed Oculus client in the default c:\ folder, and you're using a 64bit so.

In case of WMR headset WMR has the default manifest in:

c;\windows\system32\MixedRealityRuntime.json

Note. Unfortunatley Minecraft OpenXR right now is very buggy, the control are not optimal, left hand is not traced and in my system the framerate is locked at 60hz for no visible reason ,made it unpleasant to use.