وَ«هَلْ» لِطَلَبِ التَّصْدِيقِ فَقَطْ
Hal is used only to seek assent.
هَلْ جَاءَ صَدِيقُكَ؟
Did your friend come?
The question asks whether the arrival occurred; “yes” or “no” is an appropriate answer.
أَصَدِيقُكَ جَاءَ أَمْ عَدُوُّكَ؟
Was it your friend who came, or your enemy?
The second question seeks to identify an individual, so it employs hamzah with connected am. Hal does not take over that conception-seeking role in the same construction.