score:2
The most nearest potential person only within my knowledge is Meiji Emperor.
Though unlike the Hawaii Kingdom, which lasted only 100 years (from 1795 to 1893), and sizes and population is not comparable, the Imperial Japan hired may non native Japanese advisers under the rulership of Emperor Meiji. There is even an list in Wiki.
From agriculture to military issues to arts, there were almost 2,000 - 3,000 who served or advised the government (and to the Emperor). You can find a name of non native persons and what they did from the above wiki list.
So you question
Was Kamehameha I unique in elevating so many foreigners?
would probably be No.