default or selected kernelversion does not have config value CONFIG_OBSOLETE_OSS.
Result is shown for kernelversion 5.10.188

Obsolete OSS drivers

configname: CONFIG_OBSOLETE_OSS

Linux Kernel Configuration
└─>Device Drivers
└─>Sound
└─>Open Sound System
└─>Obsolete OSS drivers
In linux kernel since version 2.6.21.1 (release Date: 2007-04-27)  
This option enables support for obsolete OSS drivers that
are scheduled for removal in the near future since there
are ALSA drivers for the same hardware.

Please contact Adrian Bunk <bunk@stusta.de> if you had to
say Y here because your soundcard is not properly supported
by ALSA.

If unsure, say N.