Yep, I already used it with Lore Group earlier this month booking a stay with them in London. Check post #640 from GHA Insider higher up the page. There are few, not many, but a few at least, that allow you to use Discovery Dollars at the point of booking.

It looks like this below, and combined with the possibility of purchasing D$ with a potential discount once in a while, it is certainly more feasible and makes me far more likely to stay if I can plan to purchase D$ in advance. According to the invoice from Lore Group, it is started off with a GHA Discovery Dollars credit at the start of the bill. However, I believe you cannot use it for taxes and some other fees, so you still need to pay some, I am afraid. I got caught out by that when I did it recently, unfortunately.