If you give a QComboBox a python instance that implements the sequence protocall, you get a list back

from __future__ import print_function

from PySide2 import QtWidgets

class MyItem(object):
    def __init__(self, name):
        self.name = name

    def __repr__(self):
        return '<MyItem({})>'.format(self.name)



class MyContainer(object):
    """docstring for MyContainer"""

    def __init__(self, items):
        self.items = items

    def __len__(self):
        return len(self.items)

    def __getitem__(self, index):
        return self.items[index]

    def __repr__(self):
        return '<MyContainer({})>'.format(', '.join([repr(item)
                                                    for item in self.items]))


if __name__ == "__main__":
    app = QtWidgets.QApplication([])
    container = MyContainer([MyItem('Jim'),
                             MyItem('apple'),
                 MyItem('dinosaur')])
    print(container, type(container))
    combo = QtWidgets.QComboBox()
    combo.addItem('container', container)
    container_from_qt = combo.currentData()
    print(container_from_qt, type(container_from_qt))
    assert type(container) == type(container_from_qt)