The DevHub can be enabled in Production environment. Work with your system administrator to get it to enable. If you are experimenting or learning please sign up for a developer account developer.salesforce.com/signup or a Trailhead Playground and you can enable DevHub there.
If you plan to use Github actions you can view a helpful session ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-2fjqhwgwgCE.html You can see sample workflows using Github actions on any of the Sample apps. One example is here github.com/trailheadapps/ebikes-lwc
