Thanks for the welcome, and for that beta!
Lenses are definitely one concern since the officially supported Nauticam options are pretty limited (though to be fair to Nauticam the Fuji lens lineup is pretty sparse to begin with). Hopefully lots of new lens options will become available in the coming months as Fujifilm are finally opening up the X-mount to third parties. For wide angle I have an N85 port that should work with a manual focus fisheye such as from 7artisans or Nikkor that I plan to just preset the focus and aperture on before jumping in the water. For macro I have an N85 port that should work with the Fujinon 60mm 1:2 macro lens. That port should also work with the 18-55mm f/2.8-4 zoom lens with the 16mm extension tube which would give 0.97x magnification at an effective f/5.3 and it would definitely work with the 11mm extension tube which would provide 0.69x magnification at an effective f/4.5 (if my calculations are correct). I also have the E-mount N85 Nikonos adaptor, which may or may not work (the internal diameter of the E-mount is significantly wider than that of the X-mount).
Another concern is the aperture rings on XF lenses. If I was using a zoom lens I’d have to shoot in program-shift mode to get any say in the aperture while maintaining zoom functionality (short of buying a port extension that has its own focus knob). Or I could use the XC lineup of lenses but it seems silly to get entirely different lenses for use underwater. How much inconvenience am I willing to put up with to use my Fuji underwater? Lots to think about!