Tons of image tutorials from Reddit will probably be destroyed. This reminds me of when Photobucket wiped tons of contents which were used on old forums.

This was great, I'd love to do something like this but all my group chats are on WhatsApp or Signal!

Both Whatsapp and Signal store their messages in a sqlite-db as well! If your device is rooted/jailbroken, extracting the data is relatively simple (see e.g. here: https://towardsdatascience.com/analyzing-my-whatsapp-databas...)

You don't need to have it rooted, you can request the information: https://faq.whatsapp.com/526463418847093/