The area of each HEALPix pixel can be derived using Ω_pix = 4π / (12 * Nside²) = π / (3 * Nside²)

Our internal area calculation does not produce the correct area. From my understanding, I believe this is due to boundaries between pixels not being defined as a typical edge/gca, which throws off our internal calculations. Approximating the boundary as a GCA leads to the area be

>>> uxgrid = ux.Grid.from_healpix(zoom=0, pixels_only=True)
>>> uxgrid.face_areas

array([0.94349613, 0.94349613, 0.94349613, 0.94349613, 1.2620424 ,
       1.2620424 , 1.2620424 , 1.2620424 , 0.94349613, 0.94349613,
       0.94349613, 0.94349613])

The expected area should be ~1.047

The faces near the equator have a larger area, with those near the poles having a smaller area.