The spec only says it returns an object corresponding to the default device. ( https://data-apis.org/array-api/latest/API_specification/generated/array_api.info.default_device.html#array_api.info.default_device)

jax.numpy returns None, so the question is whether None corresponds to the default device or not.

In [5]: import jax.numpy as jnp In [6]: jnp.__array_namespace_info__().default_device() is None Out[6]: True