It's worth noting that learning how computers work at a lower level goes down to the electronics. I've seen some repair videos go down to digging out an oscill

It's worth noting that learning how computers work at a lower level goes down to the electronics. I've seen some repair videos go down to digging out an oscilloscope and looking at what is on the bus. Good luck trying to connect the probes on modern equipment, never mind being able to afford the test equipment. It is also possible to make good progress with a cheap iron and a multimeter, learn about component properties, reading circuit diagrams, and many other relevant skills. Best of all, all of the learning is being done on what was real world hardware at one time rather than circuits designed for learning or that are isolated from the system that they would normally be part of.