I dont know if this is still revelant, but I have exactly the same problem. Have you figured it out? I know that Altium produces GD1 and GG1 as drill drawing and drill guide, which in theory should be enough for PCB fabrication house to manufacture the board, but I would rather have a nice .DRL file like other programs make. I can see the drl file when I open up the excellon .txt document, but for example it cant be read using KiCad.