Is this something for open ocean scenarios?
Absolutely not. Only seaplanes with hulls specifically designed for ocean swells would go anywhere near such conditions - and they are few and far between.
The ShinMaywa is designed to operate in conditions up to sea state 5 - conditions in the North Atlantic and Pacific exceed sea state 6 over 20% of the time in winter.
https://apps.dtic.mil/sti/pdfs/ADA487947.pdf