I have tried to learn Linux for ages, and have experimented with installing Arch and Ubuntu.
There's your problem. Try Linux Mint.
Is it an unrealistic goal to want to eventually run a computer with coreboot and a more cybersecurity heavy emphasis? I’m still a noob at this and any advice would be appreciated!
Don't try to bite off more than you can chew. Start small and easy, with a beginner Linux distro, and once you've become really comfortable with that, you can try to move onto something less user friendly.