from datetime import datetime
from typing import Any

def safe_datetime(dt: Any) -> Union[datetime, None]:
    """
    Executes a safe conversion of an object to a proper datetime.
    :param dt: An object (str, datetime or other)
    :return: datetime if conversion is successful else None.
    """
    try:
        if isinstance(dt, datetime):
            return dt
        elif isinstance(dt, str):
            try:
                return datetime.strptime(dt, '%Y-%m-%d %H:%M:%S')
            except ValueError:
                return datetime.strptime(dt, '%Y-%m-%d')
        else:
            return None
    except ValueError:
        return None