Comment by giaour

You could try looking at civic technology organizations. I felt that the work I did at USDS had a huge positive impact, and you can find private firms like Nava or Truss that work on the same / similar projects if you don't want to work directly for the government. There are similar agencies and organizations in Canada, the UK, EU countries, and some Latin American countries, too.

There are also some orgs at tech giants that work on socially impactful products (e.g., sustainable hardware teams at AWS or Azure, like the folks who work on https://natick.research.microsoft.com/), so I wouldn't rule those out entirely.