Lol, no need to apologize; it's entirely possible one day someone else will have the very same question and your answer will tell them what they need to know.
To expand on your answer a bit, though, yes indeed the microphone is located on the lightning port flex cable assembly; as a matter of fact there are actually two microphones on it. Here's a picture showing their location.
Oh, and to answer the second part of your question, yes it is more complicated than a battery replacement. Since the flex cable runs under the battery and the motherboard, both of those parts have to be removed in order to access it. Sorry to say iFixit doesn't have a guide for that repair, but there's a Spanish site called Nadie Me Llama Gallina that does.
Manuales / Apple iPhone 13 Pro Max / Flex de carga - Nadie Me Llama Gallina
The site is in Spanish but used in conjunction with Chrome's translation function, it is quite usable and very well done.