Taking example of Signal, I need to save each and every image manually to be me available outside its sandbox. Why is it like that rather than making it easy for me to use things that have been explicitly sent to me?
I have used another messaging app called Twin Me which also does something similar.
I always used WhatsApp earlier that allowed me access to the media downloaded in chats and let me take local backups but unfortunately they now allow only Google backups!
The reason Signal does this is that they consider your deivce storage ‘unsafe’, as it can be more easily accessible by other apps. AFAIK not providing the option to let you do it anyway is purely because the Signal devs don’t want to.
Threema for example has an option to save all received media to normal storage, similar to WhatsApp.
Ah, that would be bliss.