@llamallamaduck
Well as far as I know Praise the Sun was indeed popularized by Dark Souls. Hidetaka Miyazaki secretly left the pose in the game even though his higher ups told him to get rid of it because wasn't cool enough; though he never mentioned where he got the pose from.
On the religious side, it maybe derived from Thelema, a solar religion which was developed in the early 1900s by Aleister Crowley. The third morning sign preluding their Liber Resh ritual looks bizarrely similar to the Praise the Sun gesture. Here's a link: https://imgur.com/a/Mrwbj74
Or it was just loosely taken from yoga. The opening movements of Surya Namaskar practice also has a posture that briefly looks like Praise the Sun.