I don't know, I don't know anything about Sony cameras or their lenses. You tell me.
For underwater photography, you generally use the following types of lenses:
- Circular fisheye
- Diagonal fisheye
- Rectilinear ultrawide
- Mid-range zoom
- Macro
For circular fisheye, the go-to choice is Canon 8-15mm fisheye via Metabones adapter. It gives you circular at 8mm and diagonal at 15mm.
For diagonal fisheye, you can use the Sony 28mm f/2 with either the Sony fisheye converter inside a dome, or Nauticam WWL-1 on a flat port - incidentally, Sony FE is the only full-frame system supported by WWL-1. Alternatively, you can use Canon 8-15mm at its long end, or the Sony 28-70mm kit lens behind a Nauticam WACP. With Nauticam housings, you can also mount the old UW-Nikkor 15mm f/2.8 fisheye without a port.
For rectilinear ultrawide, Sony offers three native choices - 16-35mm f/4 ZA, 16-35mm f/2.8 GM, and 12-24mm f/4.
Mid-range zoom position (fish portraits and such) can be filled by the 28-70mm kit lens in a dome or flat port + WWL-1, or either of the two 24-70mm lenses.
Macro is served by Sony 50mm f/2.8 and 90mm f/2.8 G - the latter is regarded as one of the sharpest lenses out there for any system.
Nauticam port chart for Sony full-frame can be found here:
N100 Sony A7RIII:A9:A7II:A7RII:A7SII Rev 7.19.pdf
The full list of lenses for Sony FE mount can be found here:
Ultimate Fullframe E-mount FE Lens Guide for Sony a7 & a9 Cameras