def getRasterSublayer(path, param):

    layer = QgsRasterLayer(path)

    try:
        # If the layer is a raster layer and has multiple sublayers, let the user chose one.
        # Based on QgisApp::askUserForGDALSublayers
        if layer and param.showSublayersDialog and layer.dataProvider().name() == "gdal" and len(layer.subLayers()) > 1:
            layers = []
            subLayerNum = 0
            # simplify raster sublayer name
            for subLayer in layer.subLayers():
                # if netcdf/hdf use all text after filename
                if bool(re.match('netcdf', subLayer, re.I)) or bool(re.match('hdf', subLayer, re.I)):
                    subLayer = subLayer.split(path)[1]
                    subLayer = subLayer[1:]
                else:
                    # remove driver name and file name
                    subLayer.replace(subLayer.split(QgsDataProvider.SUBLAYER_SEPARATOR)[0], "")
                    subLayer.replace(path, "")
                # remove any : or " left over
                if subLayer.startswith(":"):
                    subLayer = subLayer[1:]
                if subLayer.startswith("\""):
                    subLayer = subLayer[1:]
                if subLayer.endswith(":"):
                    subLayer = subLayer[:-1]
                if subLayer.endswith("\""):
                    subLayer = subLayer[:-1]

                ld = QgsSublayersDialog.LayerDefinition()
                ld.layerId = subLayerNum
                ld.layerName = subLayer
                layers.append(ld)
                subLayerNum = subLayerNum + 1

            # Use QgsSublayersDialog
            # Would be good if QgsSublayersDialog had an option to allow only one sublayer to be selected
            chooseSublayersDialog = QgsSublayersDialog(QgsSublayersDialog.Gdal, "gdal")
            chooseSublayersDialog.populateLayerTable(layers)

            if chooseSublayersDialog.exec_():
                return layer.subLayers()[chooseSublayersDialog.selectionIndexes()[0]]
            else:
                # If user pressed cancel then just return the input path
                return path
        else:
            # If the sublayers selection dialog is not to be shown then just return the input path
            return path
    except:
        # If the layer is not a raster layer, then just return the input path
        return path

# coding: utf-8
from qgis.core import (QgsLayerTreeLayer, QgsMapLayerRegistry,
                       QgsProject, QgsVectorLayer)
from qgis.gui import QgsSublayersDialog

sublayers_dialog = QgsSublayersDialog(QgsSublayersDialog.Ogr, 'Title')  # Try with QgsSublayersDialog.Gdal or QgsSublayersDialog.Vsifile

root = QgsProject.instance().layerTreeRoot()

layers = []
for child in root.children():
    if isinstance(child, QgsLayerTreeLayer):
        layer = QgsMapLayerRegistry.instance().mapLayer(child.layerId())
        if isinstance(layer, QgsVectorLayer):
            print("- layer: " + child.layerName() + "  ID: " + child.layerId())
            layers.append(
                '%s|%s|%s|%s' % (layer.id(), layer.name(),
                                 layer.featureCount(), layer.geometryType())
            )

sublayers_dialog.populateLayerTable(layers, delim="|")

sublayers_dialog.show()

# Then type after some line selection, below code
sublayers_dialog.selectionNames()
# Seems buggy here because when 2nd always return 0  > Confirm if bug
sublayers_dialog.selectionIndexes()