Complex sentence: None of the Chuggers are ever seen to have a crew, although there are several human characters that the Chuggers interact with regularly, although many of the chuggers have crew doors which the chuggers can open and close on their own.
Split into simpler sentences: None of the Chuggers are ever seen to have a crew, although there are several human characters that the Chuggers interact with regularly. This despite the fact that many of the chuggers have crew doors which the chuggers can open and close on their own.