True, both networks I have in Europe don't allow it. It's one of the reasons I don't like eSIM, there are a lot more restrictions than with real SIMs. With those I can simply pull one of my cards out of my phone and put it in my tablet or 4G modem for an hour while travelling. With eSIM I have to unregister it and get a new QR every time, registering it doesn't work abroad, and they can deny activation based on the device.