There are now USB-C cables with power meters which might satisfy your curiosity (re: charging power). https://www.theverge.com/2022/1/28/22907150/usb-c-pd-cabl

There are now USB-C cables with power meters which might satisfy your curiosity (re: charging power). https://www.theverge.com/2022/1/28/22907150/usb-c-pd-cable-power-meter-100-watt-power-delivery https://www.theverge.com/2022/1/28/22907150/usb-c-pd-cable-p...