I’ve been able to connect to xhyve machine using screen:
screen ~/Library/Containers/com.docker.docker/Data/com.docker.driver.amd64-linux/tty
login is root. no password
Inside i can see docker0 bridge and gate to outside via eth0 with IP 192.168.65.2 and gateway on 192.168.65.1. However Im not able to trace how it translates to OSX routing aaaand my network-fu skill is wayyyy too low to grasp such knowledge 
Maybe someone could shed some more light and/or try to propose some kind of solution 