As a U.S. citizen living abroad, you are eligible for U.S. Federal financial aid, just as if you resided in America. The Pell grant, however, has income requirements so you would need to meet these in order to receive a Pell. Here is some more information about Pell grants and other Federal financial aid: https://studentaid.ed.gov/sa/types/grants-scholarships/pell
Federal financial aid eligibility is determined by using your Expected Family Contribution, which is explained if you follow the link above. If you are under age 24, your parents’ income and assets will be included in your EFC calculation. If you are 24 or older, only your own income and assets will count. Sometimes a student who is under age 24 may be “emancipated” for financial-aid purposes. (This applies to veterans, students with a spouse or dependents, orphans, wards of the court, graduate students, and occasionally to others with extenuating circumstances.)
When you contact U.S. colleges … whether it’s to apply or merely to gather information … be sure to state clearly right up front that you are an American citizen because this can play a key role in how the college responds to your interest.
U.S. citizens living abroad can be very attractive to admission committees because they bring to campus a diversity of experience that many domestic students don’t offer, and yet it won’t cost the college a whopping amount to enroll them because Uncle Sam may pay part of the tab.