QF is VERY tight on D and even C inventory at the moment, still major capacity issues into and out of Australia from many countries. I've seen D on SYD-DFW, but couldn't find any to LAX despite having 2x SYD flights on some days, 1x BNE, and 1x MEL. I saw lots of days with only J for both LAX and DFW when I was looking last month. (Those were for December flights). Reckon it'll get a lot better once they get more A380s back online. I've also seen D on SCL-SYD, if you want to take AA down to SCL and connect.

If you can afford the extra segment, you'll have better luck getting AA 72 or 73 via LAX (sounds like you're going south, so AA73), sure it's not as good as QF, but at least they have wifi available, QF is still waiting on the next gen satellites before they invest, saying 'maybe' 2024.