Are there any copyleft/open source projects that you would recommend contributing to? Are there any projects that directly support leftist causes/goals? (Ex: Housing, Climate Change, Prison Abolition, Unions/Co-ops, Anti-🧊, Mutual Aid, etc.) This is not an exhaustive list at all.
Accessibility direly needs more volunteer work in almost all projects. So you could, for example, pick your favorite desktop and get involved in their accessibility efforts (e.g. start here for KDE).