Run the command:
cat <<EOF >/etc/apt/sources.list.d/octarine.list
deb https://repo.pureos.net/pureos octarine main
EOF
then do:
sudo apt update
and then run the command:
sudo apt install dino-im/octarine dino-im-common/octarine
Two things about the octarine repository:
1 - It has a lower pin priority than landing and byzantium, meaning that packages from octarine need to be explicitly selected to be installed hence the extra /octarine in the package name when installing. It also means that if you add the repo octarine to your sources your system will not be “flooded” with packages from octarine in an update.
2 - A word of caution, the octarine repository serves as a “playground” for developers to work on packages before releasing them to landing. It is akin to Debian Experimental.
The Dino package is working, BUT if you go around explicitly installing other packages from octarine, expect breakages.
(and bug reports on those breakages are welcome 
)