The XR registry is doesn't contain 'Pico' as a vendor/author? When do you plan to officially register Pico extensions?
For reference the latest registry spec is here:
As an aside, I defintitly prefer the latest release with separate openxr_pico.h as this simplifies the use alongside the existing public release of the OpenXR SDK
Thanks, we will check your question with the team, and get back to you if any updates.