The selling soul thing is from folklore and is a metaphor for those who have dark triad character traits, it’s not a real concept in practical magick. You cannot sell what you do not own. And the “dark lords” are Left Hand Path: the path of self.
Devotional worship exists, because some humans will always be sheep and need it. We humans are the ones that created the religions such as Demonolatry and Luciferianism to include an element of this. The entities will allow you to be you, and don’t really mind, imo, as long as you’re working on improving yourself.
To me, worship is the worst disrespect you can commit in the face of brings trying to get you to ascend. But we all have to start somewhere. Welcome and good luck.