Covered California’s definition of household (for household income and number of people) is given at Who is included in a household? | Covered California™ . There is also a page for college students: Students | Covered California™ .
https://www.healthcare.gov/income-and-household-information/household-size/ (referenced from a Covered California page) does say that for those who are single with no dependents:
- If you aren’t claimed as a tax dependent by someone else and have no tax dependents yourself: Count only yourself in your household.
- If you are claimed as a tax dependent by someone else: You’re counted as part of their household, not your own.
If your income is low enough, you can get MediCal (Medicaid). If your income is somewhat higher, you can get private insurance with subsidy through Covered California. If your income is higher still, you can still buy private insurance without subsidy through Covered California.