I am not an HDMI guy, but the HDMI standard supports 176 KHz and 352 KHz PCM. So, if the graphics drivers supported those sample rates, theoretically, you could send DoP over the HDMI, at least for DSD64 (1x) and DSD28 (2x), since DoP for those is 176 KHz and 352 KHz PCM. Unfortunately, most receivers that accept DSD over HDMI only process native sample rate DSD, not DoP. The HDMI support on those receivers were designed years ago to get DSD signals from SACD players, which only sent native sample rate (2.8 Mhz) SACD. So, DoP is not an option unless some manufacturer makes their receivers understand 176 and 352 KHz DoP.
Neither native sample rate drivers on PCs nor DoP support on receivers is likely to happen, given the low volume of DSD music, although there are always rumblings that NVIDIA might do it in their drivers.