how to get XFile populated with images from flutter project assets?

You can use rootBundle from the services.dart package. Import the package like this:

import 'package:flutter/services.dart' show rootBundle;

And call the following function to get the image from asset and populate XFile:

Future<XFile> getImageFileFromAssets() async {
    final byteData = await rootBundle.load('./assets/image.png');

    final file = File('${(await getTemporaryDirectory()).path}/image.png');
    await file.writeAsBytes(byteData.buffer
        .asUint8List(byteData.offsetInBytes, byteData.lengthInBytes));

    XFile xFile = XFile(file.path);

    return xFile;
  }