Given that you likely also have cable adapters and you need 1 primary key + 1 backup anyway, my recommendation would be to buy 1 usb-a and 1 usb-c. Or you can

Given that you likely also have cable adapters and you need 1 primary key + 1 backup anyway, my recommendation would be to buy 1 usb-a and 1 usb-c. Or you can make your own :) iPhone/iPad is currently not solved, hopefully with iOS 13 we'll see positive news.