如果php字符串在geojson数组中

I am trying to make a selection of country names via php, then do a check against my geojson to see if the country name I got from php matches any names in my json and if so, read the coordinates of it.

So basically I have ALL the countries in the geojson but only those that are found to match with my php variable get drawn with polygons. The example is using leaflet, what if those countries where coloured only if my php variables with the country names matches?

I have a php string which i get like this:

$myCountry = get_field("country");
echo $myCountry;

String name result is Australia

This is the var_dump of get_field()

 array(3) {
  ["country_name"]=>
  string(9) "Australia"
  ["city_name"]=>
  bool(false)
  ["state_name"]=>
  bool(false)
}

I have a geojson like this

 "type": "Feature",
    "properties": {
        "sovereignt": "Australia"
    },
    "geometry": {
        "type": "MultiPolygon",
        "coordinates": [
            [
                [
                    [-77.53466, 23.75975],
                    [-77.78, 23.71],
                    [-78.03405, 24.28615],
                    [-78.40848, 24.57564],
                    [-78.19087, 25.2103],
                    [-77.89, 25.17],
                    [-77.54, 24.34],
                    [-77.53466, 23.75975]
                ]
            ],
            [
                [
                    [-77.82, 26.58],
                    [-78.91, 26.42],
                    [-78.98, 26.79],
                    [-78.51, 26.87],
                    [-77.85, 26.84],
                    [-77.82, 26.58]
                ]
            ],
            [
                [
                    [-77, 26.59],
                    [-77.17255, 25.87918],
                    [-77.35641, 26.00735],
                    [-77.34, 26.53],
                    [-77.78802, 26.92516],
                    [-77.79, 27.04],
                    [-77, 26.59]
                ]
            ]
        ]
    }
},