Are there examples of passengers' Micro SD cards or USB flash drives surviving crashes? Are there any well-documented cases of Micro SD cards or USB flash drives surviving 100% hull loss crashes? I'm asking about cards held by passengers, not ones that are part of the aircraft's systems.
Yes. Some videos where recovered from the germanwings crash. See this article talking about it: link

The video can now easily be found online. I recommend against it tho.