Collabora has announced the Monado now provides an officially conformant OpenXR implementation, based on running the OpenXR conformance test suite on a simulated device.
Note that OpenXR 1.0 conformant status applies only to the simulated device. Anyone building a product using Monado with non-simulated hardware still needs to go through the full, normal adopter and conformance process to be OpenXR conformant and take advantage of the benefits.