You can join local Open Source group and help
You can volunteer to teach in local schools (Woz used to do that - https://www.vice.com/en/article/kb7y3v/steve-wozniak-was-my-... )
You can join one NGO you agree with and work for/with them e.g. https://media.ccc.de/v/36c3-11008-server_infrastructure_for_... In this talk Julian will outline his work as sysadmin, systems and security architect for the climate and environmental defense movement Extinction Rebellion. Responsible for 30 server deployments in 11 months, including a community hub spanning dozens of national teams (some of which operate in extremely hostile conditions), he will show why community-owned free and open source infrastructure is mission-critical for the growth, success and safety of global civil disobedience movements. )
You can do podcast / video / zines to help using technology for 'good'