It took several weeks but I finally got my Reddit data export for my account. If it wasn't already obvious, the direct messages there are not encrypted in any meaningful way. One interesting variable I found was in the file named "statistics", there's a variable named "is_deleted" which is set to false. This makes me wonder if, when you "delete" your account, they just flip this variable to disable login but still retain all of your user data. The file names are pretty self explanatory on what they contain, but the if you're curious, the files in the export are:
account_gender.csv
approved_submitter_subreddits.csv
chat_history.csv
checkfile.csv
comment_headers.csv
comments.csv
comment_votes.csv
drafts.csv
filelist.txt
friends.csv
gilded_comments.csv
gilded_posts.csv
hidden_posts.csv
ip_logs.csv
linked_identities.csv
linked_phone_number.csv
message_headers.csv
messages.csv
moderated_subreddits.csv
multireddits.csv
poll_votes.csv
post_headers.csv
posts.csv
post_votes.csv
reddit_gold_information.csv
saved_comments.csv
saved_posts.csv
scheduled_posts.csv
statistics.csv
subscribed_subreddits.csv
twitter.csv
user_preferences.csv
Yeah my whole export was only like 3MB of CSV files, so I'm guessing that any media you upload just gets dumped into a giant bucket with everybody else's stuff and then referenced by your post or whatever. Kinda makes you wonder if that stuff gets deleted if you delete your account.