We had these mischievous-evil things, too, many kinds of them, in fact, but we don't call any of them "devils" (incidentally, what I presume you're referring to as "devils in the Scandinavian folklore" get translated to one or several of those in Estonian, since I've never even seen anything called a "devil" mentioned in relation to Scandinavian folklore, Estonian ot English - when I've read about Scandinavian folklore, then almost always in Estonian, granted -, but I've seen some of these other things mentioned) ... the devil didn't exist in Estonian folklore before early Christian influences (devil as in the same word as the Christian devil, and deity-level entity or primary force in any other context), and then he was - depending on the story and region - either pretty much fully omnipotent, or the contract-bound, but otherwise omnipotent soul-collector sort (god, in turn, always remained strangely absent and never actually did anything whatsoever). And there is another rift between the stories where the corresponding figure is actually referred to as a devil, and the later variety, in which he again isn't called as such.
The actual Christian devil ... is what he is; while he isn't considered a deity by other than satanists, he nevertheless is the closest thing the other side has and also the superior of all demons. Granted, if we start talking of what different cultures see different entity-classes as, it often just ends up being a matter of what word you map to what other word in another language... Often enough, it can consequently vary immensely by which translation you read.
(As far as gods always being painted as supreme beings goes, a "tormented/starving soul" is any entity at the lowest wheel-of-life state of existence where they exist in utter suffering, and "god" is actually any entity at the highest wheel-of-life state of existence where they have everything and are awesomely powerful in some branches of Buddhism - once interpreted to English, anyway. And in this instance, "god" isn't necessarily a deity... Meanwhile, non-god deities are at least referred to (be they implied to be real or just personified-for-story-purposes phenomena), though never worshipped, in other places of the same branch of the religion, often even in the same scripture. I don't think I've seen any other word but "god" used in that case, in Estonian or English. So... Yeah, there absolutely are interpretations of the word "god" which are either non-deity or at least nothing to look up to, one example given. And then there are the countless very minor and/or mortal gods found in various religions...)
- Admittedly I can't speak much on D&D ... I've wanted to try it, on and off, but it never worked out on the organization-side, so there it has been left, and I don't know much of the lore hence. (Unless you want to count playing Baldur's Gate II, which I don't know how canonical is...)
Not sure where I wanted to go with it, but I guess the point is that your interpretation may vary depending on whose lore (and which translations ... perhaps especially which translations) you've read... Mine just have happened to cement "devil" as a handful of orders of manitude more powerful than anything called a demon (including devils slaying them and their higher orders by tens of thousands), and ranked gods and devils as equals...
As a sidenote, Estonian folklore didn't have gods, either. There were untold spirits, though...
On a random thought, given how many mythologies have their original creators eaten/slayed/imprisoned/stripped of power and/or damned eternally by their successors, who created who might not be the best way to determine rankings or relative power...