MSI has not started selling its first 500 Hz QD-OLED monitor globally yet. Nonetheless, it has not unveiled its second and likely cheaper option, which it will release later this month as the MAG 272QP X50.https://www.notebookcheck.net/MAG-272QP-X50-MSI-presents-new-500-Hz-gaming-monitor-with-27-inch-QD-OLED-display.1012427.0.html
Just to let you know TFTCentral has confirmed that the only 4th Gen QD-OLED monitor available this year will be the 27" 4K 240Hz panel using EL 3.0. The 27" 1440P 500Hz is Gen 3 and using EL 2.0. Samsung Display confirmed this to TFTCentral recently.