제 고향은 미시간 이에요.
남편의 고향은 미시간 이에요.
친구의 고향은 충청남도 이에요. -> 충청남도예요 (since 도 ends with a vowel)
They are all good except that 이에요/예요 attaches to the noun with no space. It is equivalent to the "be" verb in meaning, but it's treated like a particle (kind of like the "I'm" contraction, but it is always written without a space - adding space before 이에요/예요 is a grammatical error).
"남편 고향" and "친구 고향" are very natural. In fact, we use these shortened form most of the time dropping the possessive 의.
And 고향 can be used for both a state and city. A city is probably the smallest area you'd say for 고향 (e.g. 고향이 부산이에요 is commonly heard).