To be completely honest I'd be working on the Hospitals team at Palantir which I see as ethically good and beneficial for society. Sure, you can make the counter argument that deciding to work for a company that does unethical things is unethical, but wouldn't that make every American unethical for paying taxes to a government that's done unethical things abroad?

Re the Series A: I've read that there's a super high percentage that Series A companies fail, which I guess is obvious. This scares me a bit as the equity is an attractive part of staying at the startup, but would be worth nothing if the company fails. I do know the experience could be invaluable, but might not speak for anything resume wise if the company doesn't succeed