Could a bronchoscopy be done at the doctor's office?

Not usually. Because conscious sedation (iv medications) are used during the procedure it is done in an outpatient endoscopy suite (usually associated with a hospital); most doctors do not do bronchoscopy in their office for this reason.
Adding.... ..To what dr. Milstone said, which is generally true, because the requirements for conscious sedation make it difficult. That said, there are doctors offices where bronchoscopy can be done. The fact that it most often is not done, does not mean it cannot or should not be done in an office setting. I work in an clinic where we have an ma and nurse that oversee conscious sedation when needed.