> Do junior positions exist that engage politically while still providing the sort of technical engagement and creative freedom found in a smallish software shop?
I think the best place to do this has been at the USDS (United States Digital Service) or 18F, which operate like startups inside the federal government. But their funding appears to be threatened by the outcome of the election, so it's unclear what'll happen there.
You could also consider working on topics like user privacy, crypto, decentralized systems. I agree it's hard to get hired for -- or even just get experience with -- distributed systems while you're still a junior programmer.
> Could it be better to work a satisfying, apolitical position and simply donate to the organizations we care about?
Yes, see the "earning to give" approach in effective altruism: https://en.wikipedia.org/wiki/Earning_to_give. (One worry is that people tend to share priorities with those they're surrounded by, so taking an apolitical position -- e.g. at a hedge fund -- could change your politics unexpectedly.)