Yes, we can confirm that the Dual Dock Stand will support dual extended display when used with a MacBook Air M4. 

Please note the resolution and refresh rate for each combination:

2x HDMI at 4K30Hz for both

1x HDMI (4K30Hz) and 1x DP (4K60Hz) for each display

macOS users will have to change one of the display's resolutions to 1440P (low resolution) to achieve 60hz on both displays.