I think it really depends on what you mean by "moonlight." Most reef keepers who put "moonlights" on their tank are not coming anywhere near to imitating natural moonlight on a reef, and of course that's OK if it's what you want. I'm struggling to find it now, but when I began my LED journey a few years ago I found a website that provided spectral and intensity data for real reefs in the pacific, 24/7. Moonlight was incredibly dim. And, it was pretty much the exact same spectrum as daylight (which makes sense, since it IS daylight, just reflected off the white moon). By comparison, what most reefers put on their tanks is much brighter, and much bluer.
I'm not really familiar with off the shelf moonlights but if you wanna think about DIY lemme know, it would be pretty easy to fab something that was controllable and whatever color/intensity you wanted.