The idea of the gallery in the chat profile is great, a quick way to search for attachments grouped in one place.
However, sometimes I work by reviewing chat chat searched for a photo / attachment, because I don’t remember who sent it to me,
SO:
I recommend that a General Gallery be made, similar to the one we have, but where the attachments of all the chats are grouped.
Access to it could be in: options / General Gallery
yip, this would be super-useful. in fact, we have similar ideas and plans 
funny enough I was struggling with this and wishing this feature while working with Delta Chat yesterday
I want to add something else:
Currently when we open an image from the Chat, we have the option to open the gallery , but when we open the image from the gallery we have the option "to open gallery"
I suggest that when opening the image from gallery, have the option to open the corresponding message.
The idea is to replace the “all multimedia” option with “view messages”, when the image is opened from the gallery.
yip, also this makes totally sense sth. “as long click → show messages in chat” came into my mind. and/or a button in the enlarged view.