Thank you for the advice - greatly appreciate it! Regarding your comment:
> if you have solid experience as a full stack web developer then I would suggest finding a way to pivot off that expertise (web application security, infrastructure, etc) rather than diving into the Shellcoders Handbook, x86, and K&R, which are going to be more tailored towards reverse engineering and vulnerability research.
I've been focusing on those areas because they are what legitimately fascinate me. I enjoy web dev, but I'm finding my passion (as indicated by what I like to research and learn about in my free time) is low-level stuff: operating systems, C programming and associated vulnerabilities, assembly language, etc.
The interaction between software and hardware has always fascinated me (1997 when we got our fist computer: How does this hunk of plastic and silicon do that??), and I feel like that's where I want to go long-term.