How is the Estonian system now? I remember when I visited around 2010 our host just had a quite simple smart card reader and could just use it to sign in to government services with their ID and as far as I remember even sign mails and documents. Germany of course could not use normal smart cards but had to use NFC cards with special readers and made the signing feature and additional service you had to pay for on a yearly basis. Of course the Germans system did not went anywhere for years. I do have a reader now and can use it for some governmental services and have very limited appetite to bind the ID to my phone.