Sony is demonstrating an early-stage MR headset, based on dual 1.3" 4K OLED microdisplays (or at least this is what is assumed, as Sony did not exactly detail the displays). The headset, which isn't yet a product, uses Qualcomm's XR2+ Gen 2 processor, includes passthrough video (soft-AR), and unique controllers. Sony said its headset is "primarily designed for professionals who work with 3D".
It is likely that this headset uses Sony's ECX344A displays - which are actually 1.41" 4K (3552x3840) OLED microdisplays, announced in August 2023. These same displays are used by Apple in its Vision Pro headset.
Sony says that in order to develop the new display it developed new miniaturization processes as well as a new pixel drive circuits and a high-speed driver circuit. Sony says that the price of each panel is set at 150,000 Yen, or just over $1,000 USD (it is estimated that Apple pays around $350 for each panel).