> Do you have any recommendations for types or scope of personal projects?
you're in a really great place to teach yourself because colleges will generally have hands-on, free help. Beyond that I would say get projects that people or business need - you'll be way more incentivized to learn. An internship with a small startup where you work for cheap would be a really great starting place. It's a tradeoff - cheap labor for them if they're willing to help teach you.
For security & systems, look for backendy, devops, or rel-eng. opportunities. You'll quickly learn a lot.
I got a degree in public relations and took a job doing tech sales at a Series A company. I was the 6th employee. The product was pretty unstable so I taught myself to code to improve their QA infra.(basically writing automated tests). I went on to build product for them.
Now I work as a SWE at FANG (not Amazon).
I definitely remember feeling like you did before I joined my first big company, but fortunately it's working out. Happy to answer any q's you might have along the way.