A chat thread is a poor photo archive
A chat scrolls away and usually sends a smaller photo. A Chest keeps the uploaded file in one place.
A wedding chat is good for the day and poor as the album. Messages scroll away. The photo in the thread is often a smaller copy. Finding one picture later means searching the conversation.
OurChest does not include a chat. Guests join the Chest with a display name and add photos there. There is no password. OurChest keeps the uploaded file and does not make a smaller copy for the Chest.
The Chest is not a copy inside the chat app. OurChest does not import a chat archive in the first release.