I'm a CS student, I have some time before I graduate and have kind of dipped my toes in various things without specializing in anything. I would like to know what would be useful for the movement, so that I can use my skills to contribute.
And before people say "everything is useful"...well yeah but it's nice and fulfilling to have specific ideas I can work on learning/building myself.
Also where can I find leftist open source projects? I know lemmy and this website for one are open source but not sure of others.
As a software engineer, I asked myself this question a lot when I was in school. Probably, the biggest is enabling secure communication, learning how to hide your footsteps and the footsteps of others. Secure web design, development, hosting is a big one, on top of all of the problem solving techniques you will actually be learning. I find myself benefitting greatly from working on huge projects that would have seemed daunting to me a long time ago, it's a really useful skill to take something very big and break it down into pieces until none is left.
Outside of that, the best thing you could do is organize. Join an organization if you haven't already. Meet people in your community, support striking workers, etc.