Ownership and permissions on devices. Normally, devices should be owned by root and permissions should be as restrictive as possible. However, normal users may have legitimate reasons to e.g. write to devices. Block and character devices. Major and minor numbers.
Numbers are the means for the kernel to recognize the devices.
Drivers and the kernel Kernel configuration. There are submenus for various categories of devices. Compiling into kernel vs modules. Compiling into the kernel increases the kernel size. Loading modules takes some time.