@muskist No, there is no space left, your root-filesystem ("/") is 100% in use, and that's why apt update and/or apt install fails. But I don't know why your root-fs is so small, on my Volla22 it's 7,1G and 2,9G are used, so there is enough space for thing like that.
AFAIK the porter of your device has to declare the size of the filesystems.