official linked preparation for the LPI DevOps Tools Engineer Certification, covering software engineering, machine deployment, container & configuration management and service operations
When someone wants to play a bit more with git: learngitbranching. If you afterwards want to rewrite history, watch the lets fck up history talk.
update I found the beautiful Oh my Git from bleeptrack and blinry, where you can try all that (low level) git operations in a Linux VM in your browser.