WebXR does have a Layers feature WebXR Layers API Level 1, where you may integrate html elements into your scene. I have never used it, & it is not currently implemented in BJS.
Even if it were, Native does not have a dom, so there is not going to be an OpenXR equivalent.
Also from a performance standpoint, the weakest XR area currently is that multi-view is not supported at this time. Getting it working will get a far better improvement than “going native”. My view of the primary goal of native is so there is a light weight deployment option outside of a browser, like an apps store.