geohash.kql

// Geohash GeoJSON collection
datatable(lng:real, lat:real)
[
    -73.975212, 40.789608,
    -73.916869, 40.818314,
    -73.989148, 40.743273,
]
| project geohash = geo_point_to_geohash(lng, lat, 5)
| project geohash_polygon = geo_geohash_to_polygon(geohash)
| summarize geohash_polygon_lst = make_list(geohash_polygon)
| project pack(
    "type", "Feature",
    "geometry", pack("type", "GeometryCollection", "geometries", geohash_polygon_lst),
    "properties", pack("name", "Geohash polygons collection"))

map.geojson

{
  "type": "Feature",
  "geometry": {
    "type": "GeometryCollection",
    "geometries": [
      {
        "type": "Polygon",
        "coordinates": [
          [
            [
              -74.00390625,
              40.78125
            ],
            [
              -73.9599609375,
              40.78125
            ],
            [
              -73.9599609375,
              40.8251953125
            ],
            [
              -74.00390625,
              40.8251953125
            ],
            [
              -74.00390625,
              40.78125
            ]
          ]
        ]
      },
      {
        "type": "Polygon",
        "coordinates": [
          [
            [
              -73.9599609375,
              40.78125
            ],
            [
              -73.916015625,
              40.78125
            ],
            [
              -73.916015625,
              40.8251953125
            ],
            [
              -73.9599609375,
              40.8251953125
            ],
            [
              -73.9599609375,
              40.78125
            ]
          ]
        ]
      },
      {
        "type": "Polygon",
        "coordinates": [
          [
            [
              -74.00390625,
              40.7373046875
            ],
            [
              -73.9599609375,
              40.7373046875
            ],
            [
              -73.9599609375,
              40.78125
            ],
            [
              -74.00390625,
              40.78125
            ],
            [
              -74.00390625,
              40.7373046875
            ]
          ]
        ]
      }
    ]
  },
  "properties": {
    "name": "Geohash polygons collection"
  }
}