So, actually I am using raspberry pi with OS version Stretch and kernel version 4.14.98-v7+.
I need to add kernel module for wifi module I use from this repo: https://github.com/LairdCP/Sterling-60-Release-Packages/releases
While on it, I check that it is supporting 4.19 kernel. I am thinking to download the linux source for 4.19 kernel from this : https://github.com/raspberrypi/linux
I have read that I can build my own kernel: https://www.raspberrypi.org/documentation/linux/kernel/building.md
Is there a way to compile the kernel source including the external module?