Hey thanks for the solution. Thought the link https://localhost.rig.twitch.tv:8080/panel.html does not work for me. It says This site can’t be reached localhost.rig.twitch.tv’s server IP address could not be found.
I ran yarn start and the React component works fine on browser https://localhost:8080/panel.html. Then I found on DevRig I should not click Run Front End, the it would show by itself. Not sure whether it is the correct way to run Boilerplate.
By the way I changed generate_cert.sh according to this post: https://github.com/twitchdev/extensions-boilerplate/issues/1