There are so many kinds of water you can create, even for mobile.
Anyway, it depends on desired reference and performance. I think you can simply take ocean material from WaterPlanes example project and optimize for your needs.
If I had to create ocean for mobile, I’d make it unlit and opaque, use big and small waves (but one normal map), one or two colors with variation, add foam if there is some reefs/islands, and maybe I’d use some additional geometry waves.