default or selected kernelversion does not have config value CONFIG_NFT_EXTHDR.
Result is shown for kernelversion 6.7-rc3

Netfilter nf_tables exthdr module

modulename: nft_exthdr.ko


Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>Network packet filtering framework (Netfilter)
└─>Core Netfilter Configuration
└─>Netfilter nf_tables exthdr module
In linux kernel since version 3.13 (release Date: 2014-01-19)  
This option adds the "exthdr" expression that you can use to match
IPv6 extension headers and tcp options.

source code: