The cable of MetroY Pro is for 12V , absolutely donβt use it with any other scanner.
It will violate the warranty as well if something happens, you also risking damage of the rechargable battery or fire hazard.
I remember someone used it by accident and burned down the scanner.
If you keep the power supply on all the time you going to kill the MIRACO battery very fast and after that you will need to replace it as without battery the device will not start anymore , so for both question , absolutely NO.
I did tried a USB split cable with MIRACO to charge it while using on my PC but it did not worked at all using various cables .