Not sure how it is related. Unit is an app server, it runs app processes and manages them, handles graceful restarts and etc.
Kong is just an API gateway: you run your own infrastructure as usually and put a gateway on top of it.
Kong is just an API gateway: you run your own infrastructure as usually and put a gateway on top of it.
Not directly related as Unit seems to be advertised as app server primarily, but you can see quoted text on main page.