[F2]

Halbach arrays are just a pattern or orientation of magnets that biases the total magnetic field to one direction.[1]

Polymagnets are just magnets with a pattern of multiple north-south poles on one face. [2]

At best you could have a Halbach array on a single polymagnet and have it be just as effective as individual magnets in the same pattern.

Though for large scale applications there wouldn't be much point as you could just use cheaper off the shelf magnets.

[1] https://www.kjmagnetics.com/images/blog/halbachvsalt.png [2] https://i.imgur.com/Nz9QJTV.png