Although they're often referred to as a flight computer, in fact, the E6B is nothing more than a fancy circular slide rule typically made of sheet aluminum; photo below.
View attachment 164502
Your description of the radio compass is fairly accurate, I will only add that the radio stations (way points) the radio compass points to are ground based and are scattered across the US. Sometime back in the 70's (I think) avionics companies developed the R-Nav which would pick up multiple way point stations and tell the radio compass to display a heading to your destination instead of to the way point. R-Navs were the forerunner to GPS. Those of us who got our US pilot licensee back in the 80's were still required to learn how to navigate using way points and radio compass,...no R-Nav and no GPS allowed.