The ROS publisher/subscriber example packaged as a snap, based on ROS Noetic and Ubuntu Core 20. Strictly confined. This example is available on ROS wiki, here.

Just launch snapcraft from top dir, it will create the snap publisher-subscriber_0.1_xxxx.snap

snap install publisher-subscriber_0.1_xxxx.snap --dangerous

Open a shell then launch roscore

publisher-subscriber.roscore

Open a shell then launch the talker

publisher-subscriber.talker

Open a shell then launch the listener

publisher-subscriber.listener