Instead of storing the name of the owner/assigned user store an association to this user, e.g. Module.Package_User_Owner and Module.Package_User_Assigned. Then your XPath becomes easy
//Module.Package[Module.Package_User_Owner = '[%CurrentUser%]' or Module.Package_User_Assigned = '[%CurrentUser%]']
If you NEED to do it by name instead of association (I would highly recommend an association), you need to do your retrieve on a datasource microflow. In the microflow, you can compare with attributes of your current user, on a page you can only compare to the object itself.
Can’t you use the system members in the entity? (store owner)