default or selected kernelversion does not have config value CONFIG_KUNIT_UML_PCI.
Result is shown for kernelversion 6.18-rc3

KUnit UML PCI Support

configname: CONFIG_KUNIT_UML_PCI

Linux Kernel Configuration
└─>Kernel hacking
└─>Kernel Testing and Coverage
└─>KUnit - Enable support for unit tests
└─>KUnit UML PCI Support
Enables the PCI subsystem on UML for use by KUnit tests.
Some KUnit tests require the PCI core which is not enabled by
default on UML.

If unsure, say N.