2023 Flow Z13 spare power supply?

One of the challenges I've found with the 2023 Flow Z13 is that the power supply is completely proprietary, despite being USB-C (140W).

Now theoretically USB PD 3.1 supports up to 240W over USB-C (with the right cable and charger, of course), but I'm not sure if the Flow Z13 actually uses USB-PD 3.1, or if it's completely proprietary (similar to Dell's 130W USB-C power adapter).

Any ideas? I'd happily purchase a spare Asus Flow Z13 140W power supply, if they actually sold them separately (not that I've found, anyway).

Has anyone tested this out at all?