Astrhori 6mm f/2.8 FE preorder at Astrhori and Amazon.
SonyAlphaBlog tested the new 6mm FF lens and highly recommends it:
The Astrhori 6mm F2.8 Fisheye (299$) is a unique circular fisheye with a record field of view of 220° . Results are very good to excellent in term of sharpness. Very good color rendition and bokeh but bad resistance to flare