Correct, Basically, with Wireshark and other software sniffers, you can only tap into driver level. For example, some network cards do packet CRC calculation, inside the hardware, and that information never gets to upper levels. So, the amount of information you can look at depends on that piece of software that interfaces the OS to the hardware (the driver).
Even if you can write your own driver for a network card, to try get a deeper look, I believe at most you'll get the contents of the buffer memory of the card. It won't get you information like bit timing and perhaps not even corrupted packets, as the card may discard them before pushing up to OS.