How can you export iPhone Messages (e.g. to a CSV)?

I have a friend who needs to save and document a conversation history in Apple's Messages app for legal reasons, so I'm trying to help her figure that out

I've backed up the iPhone to my mac and dug into the backup data. There's a manifest of the backup files in a SQLite database, but the actual content of the files is all in blobs of unknown format

I've seen articles from dubious sources recommending different third-party programs that will make sense of this data for you, but I don't know which if any are trustworthy

I'd be very grateful for any suggestions or ideas