Most of the listings require past experience with hardware stuff, not just CS fundamentals. I'm seeing very little interest in hiring someone like an experienced React developer who just got laid off from FAANG. There's a big difference between being theoretically capable of doing a job, and having any reasonable chance of getting hired for that job.

why did you say CS fundamentals when it's clear that it should be computer architecture and instruction sets and compiler engineering, which are a very narrow and specific parts of CS and in fact are never the parts that people refer to (DS & algo) when they say CS fundamentals.