default or selected kernelversion does not have config value CONFIG_GENEVE_CORE.
Result is shown for kernelversion 5.15.67

Generic Network Virtualization Encapsulation library

modulename: geneve_core.ko


Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>Generic Network Virtualization Encapsulation library
In linux kernel since version 4.2 (release Date: 2015-08-30)  
This allows one to create Geneve virtual interfaces that provide
Layer 2 Networks over Layer 3 Networks. Geneve is often used
to tunnel virtual network infrastructure in virtualized environments.
For more information see:

To compile this driver as a module, choose M here: the module

source code: