We can get a Geohex grid aggregation, but there isn't an option to "see" what's inside the Geohex grid with queries (i.e. someone clicks on that polygon).
From what I can gather, Opensearch only supports querying with a bounding box, Geodistance and Geopolygon. So the only option seems to be to decode the Geohex into a polygon as the filter.
I am wondering if there is a more elegant solution to filter by Geohex grid, like passing the hex directly.