Huh.
‘Drow’ is a Scottish word. A variant of Scots ‘trow’.
According to the Scots language, it is pronounced [drʌu].
As such, the Scots term sounds somewhat in between American English ‘crow’ and ‘cow’.
Interestingly, in the Scots language, Scots ‘drow’ [drʌu] rhymes with neither Scots ‘craw’ [krɑ] (English ‘crow’), nor Scots ‘coo’ [ku] (English ‘cow’).
The upshot is, Americans never pronounce the word ‘drow’ properly, the way Scots do, because American English gets the vowels wrong.
So, the American pronunciation is whichever way Americans want it to sound for Americans.
As such, the American English ‘drow’ rhyming with ‘cow’, seems to prevail. Albeit, rhyming with ‘crow’ is a significant variant.
My first D&D group rhymed it with ‘crow’. (Heh, this same group pronounces Irish ‘shillelagh’ properly!) So that is how I first pronounced it. But these days, I find myself rhyming it with ‘cow’.
Heh. That said, my dialect of American English is strongly monopthongal. (‘Mayonaise’ sounds more like [menez].) So, if I am paying attention, the way that I say ‘cow’ and ‘drow’, sounds more like [kʌ] and [dɹʌ].
This monothong [ʌ] is a (non-centralized) unrounded mid-open back vowel.