I am only putting this out on the medium.com because I had hard time googling the proper way to do it.
I am using 2021–05–07-raspios-buster-armhf-lite.img.
Testing on Raspberry Pi 3 Model B Rev 1.2.
The wpa_supplicant.conf file:
Save this file as plain text, and drop it onto “boot” partition of SD card you have prepared for your Raspberry Pi.