I doubt you will find one. You may have to re do the top to the vanity and use an under mount sink. Post a photo

Yep plus the fact hexagon sinks are a really dated look so if replacing the sink just do anew counter you will be glad you did.

Or not. My favorite sink was a Kohler hexagon.

I replace kitchen sinks for a living and occasionally get calls to replace vanity sinks. I will only take the job if the customer is getting a kitchen sink replacement. At my rates, I can't afford to cost effectively recut a vanity cutout; especially if I have to polish for an undermounted sink. The exception would be your having an exotic stone, a large area, and a large budget.

It sounds odd, but with as cheaply as most granite fabricators work, you can get a replacement top installed less expensively than you can have me replace your sink(s). Especially if you're not too fussy about color/movement/particulates and pick a remnant from your fabricator's rack.