> I think it's storing array data as-is in straight binary.

You can't infer the stride from the raw binary; a 2-D array [[1, 2], [3, 4]] in C ordering just looks like:

1,2,3,4

and in Fortran ordering it's

1,3,2,4

So there must be additional metadata stored. Maybe it's just using the .npy format internally - https://numpy.org/devdocs/reference/generated/numpy.lib.form...