I had assumed the 24-hour subdial was a chronograph function. No, it's a time indicator, essentially a repeater of the hour and minute hands. Although it indicates 24 hour time, not 12 hours. Instruction manual didn't appear to mention any of this, and I took awhile figuring this out; I don't have many chronos, and haven't seen this complication before. Seiko VK63 movement.

Edit: While "PAGANI DESIGN AEOfficial Store" listing says VK64 movement, that movement does not match the dial positions. Pagainidesign.cn does list it as having a VK63 movement. The PD-1782 has a ghost/phantom date wheel; I doubt they modified the movement to remove the calendar components, and because the manual has a "danger zone" setting warning, pretty certain they didn't. https://calibercorner.com/phantom-date/.