default or selected kernelversion does not have config value CONFIG_BINFMT_SOM.
Result is shown for kernelversion 6.5.1

Kernel support for SOM binaries

modulename: binfmt_som.ko

configname: CONFIG_BINFMT_SOM

Linux Kernel Configuration
└─>Kernel support for SOM binaries
In linux kernel since version 2.6.12  
SOM is a binary executable format inherited from HP/UX. Say
Y here to be able to load and execute SOM binaries directly.

source code: