Who Was Appointed the Imam of the Ka'bah After the Conquest of Makkah?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

It is likely to be Hubayrah Ibn Sabal Ibn Al-'Ajlān Ibn 'Attāb Al-Thaqafī . It is mentioned in Al-Istī'āb fī Ma'rifat Al-Aṣḥāb by Ibn 'Abd Al-Barr : "Hubayrah Ibn Sabal Ibn Al-'Ajlān Ibn 'Attāb Al-Thaqafī – he was the first to lead the people in congregational prayer in Makkah after the Conquest [of Makkah], and he was commanded by The Prophet to do so. He embraced Islam at Al-Ḥudaybiyah, and the Messenger of Allah appointed him as his deputy over Makkah when he set out for Al-Ṭā'if, as mentioned by Al-Ṭabarī." (End of citation)

Similarly, Ibn Ḥajar states in Al-Iṣābah: "Abd Al-Razzāq reported from Ibn Jurayj: 'I was informed that the first to lead the people in congregational prayer in Makkah after the Conquest was Hubayrah Ibn Sabal Ibn 'Ajlān. The Prophet commanded him to lead the people in prayer. He was a man from Thaqīf who came to the Prophet while he was at Al-Ḥudaybiyah.' This was likewise reported by Al-Fākihī and Abū 'Arūbah in Al-Awā'il, via the transmission chain of Ibn Jurayj." (End of citation)

Allah Knows best.