In the section Building a Kernel from the Fedora dist-git (https://docs.fedoraproject.org/en-US/quick-docs/kernel-build-custom/#_building_a_kernel_from_the_fedora_dist_git), point 5 lists the command to "Install the new kernel" as:

sudo dnf install --nogpgcheck ./x86_64/kernel-$version.rpm

which results in dnf errors around conflicting requests.

The following command installs all the required RPMs which were produced by the "fedpkg local" command:

sudo dnf install --nogpgcheck ./x86_64/kernel{,-core,-modules,-modules-core,-modules-extra}-$version.rpm