Praise be to Allah, and peace and blessings be upon the Messenger of Allah. To proceed:
The fact that there is no report of Amr ibn al-As (may Allah be pleased with him) destroying the Pharaonic statues can be explained by the fact that many of the monuments and statues known to us today were not visible or known to the Muslims at the time of the conquest of Egypt. Many of them were discovered in later periods. Furthermore, monuments that remained standing but were not worshipped or venerated as idols were different from idols that were objects of actual worship.
Over the centuries, many Egyptian antiquities became buried beneath sand and soil. Therefore, many of the tombs, statues, and monuments that we see today were not exposed in the way they are in modern times.
Thus, it is incorrect to assume that all the Pharaonic statues known today were visible to the Muslims when they entered Egypt and that they deliberately chose to leave them untouched.
The fundamental point to understand is that an idol that is worshipped besides Allah and serves as a manifestation of polytheism is not the same as a building or historical monument that people do not take as an object of worship.
For this reason, the Prophet Muhammad ﷺ destroyed the idols that the polytheists worshipped and venerated, as happened with the idols around the Kaaba and elsewhere.
The pyramids, for example, existed at the time of the Muslim conquest, but they were not temples to which people directed acts of worship besides Allah. Moreover, demolishing them would have required enormous resources and effort.
The existence of an image or statue from an earlier civilization does not necessarily mean that it continued to be worshipped or represented an active religious practice in society.
Therefore, a distinction must be made between an idol to which acts of worship are actually directed and surviving historical monuments that people do not regard as gods or at which they do not perform polytheistic acts of worship.
Judging a particular historical event also requires knowledge of the condition of these monuments at that time, how visible and accessible they were, how they were being used, and the ability of the ruling authority to deal with them.
Many of the Pharaonic statues and monuments known today were not visible at the time of the Muslim conquest of Egypt and were only uncovered in later periods. As for those that existed but were not worshipped besides Allah, they were not necessarily subject to the same ruling as idols that were taken as gods and to which acts of worship were directed.
Therefore, the survival of Pharaonic monuments cannot be used as evidence that the early Muslims approved of idol worship. Nor is it correct to treat all ancient monuments and statues as one and the same without considering their actual nature and use.
And Allah knows best.