"my time would have been better spent reviewing more basic embedded topics." In my own experience embedded topics have all been a derivative of my experience working on embedded systems( I Interviewed for a EE role). What kind of embedded questions were you asked ?
Some things relating to board bringup(power-on to when the bios boots the OS, how DDR memory is initialized, etc). Basic algorithms(bit counting), atomics, virtual memory, malloc()/free() implementations, etc. Given system X and problem Y, what could cause problem Y.
Not strictly embedded, but definitely not graph theory.
