I used civic identity because currently, if you live in Scotland your nationality (passport etc) is British, but you have a further civic identity under the law (university fees, court system etc) of being Scottish. If people who were born and brought up and living in England start referring to themselves as Scottish, it causes problems because they are not Scottish in the civic sense. Civic decisions about Scotland should be made by only the people who live in Scotland regardless of them having English, African, or Scottish parents. For that reason, people with Scottish grandparents who live in England usually call themselves English.
It is completely different with Pakistan because we don't share a border with Pakistan and are not trying to sort out a complex shared political system with them. So it is fine to refer to yourself as Pakistani when you are from Britain; everybody knows what you mean.
But if people who live in England, were born in England and have always lived in England start claiming to be Scottish, that is confusing as we are constantly in contact with people who genuinely are Scottish and live in Scotland within various entitlements granted as a result of being Scottish.
SO there is simply no way of making 'Scottish' an analogue to 'Pakistani.'