Here is a one-liner that can serve as a starting point for integrating applications with kakoune. It took me a couple of hours of experimenting, and reading docs & plugins to come up with a one-liner that demonstrates a common use-case of mine: Integrate an interactive application inside a new tmux pane with kakoune. Yes, Iām a kakoune scripting beginner but long-time user trying to level-up 
In this example, we integrate television.
From the kakoune prompt:
:tmux-repl-vertical "echo ""exec -client %val{client} \"":edit $(tv files)<ret>\"" ""| kak -p %val{session}"
Mapped to a key in kakrc:
map -docstring 'TV files' global user f ':tmux-repl-vertical "echo eval -client %val{client} \""edit $(tv files)\"" | kak -p %val{session}"<ret>'