At least on iOS - whatsapp doesn't seem to nag about backups (i don't think i've ever enabled it), but you can do a local backup/restore if you replace handset.

At least on iOS - whatsapp doesn't seem to nag about backups (i don't think i've ever enabled it), but you can do a local backup/restore if you replace handset. Signal encrypts your chats locally (but not binary blobs/video/images) but they cannot be backed up and restored locally.