CONFIG_ARCH_PXA is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_ARCH_PXA.
Result is shown for kernelversion 6.9-rc7

PXA2xx/PXA3xx-based

configname: CONFIG_ARCH_PXA

Linux Kernel Configuration
└─>PXA2xx/PXA3xx-based
In linux kernel since version 2.6.12  
Support for Intel/Marvell's PXA2xx/PXA3xx processor line.