Usually, Hilton Grand Vacations locations are available on the Hilton Honors app, but not Sandestin. But, doing a web search, it shows as an HGV resort. There is also a Hilton Sandestin resort (aka better than their hotels but not the timeshare). I have considered going there for vacation either via Hilton Honors points or buying into HGV, but that will probably be next year. I know Hilton Sandestin is a part of the whole resort complex, kinda like Wyndham Bonnet Creek Resort has a Wyndham Grand Bonnet Creek.
TS