To open url with custom label ios/android:
const scheme = Platform.select({ ios: 'maps:0,0?q=', android: 'geo:0,0?q=' });
const latLng = `${lat},${lng}`;
const label="Custom Label";
const url = Platform.select({
ios: `${scheme}${label}@${latLng}`,
android: `${scheme}${latLng}(${label})`
});
Linking.openURL(url);