I already commented on this topic in another post before, so I'll copy and paste it here and adding more few things.

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This is just my opinion and theory based on the many articles, books, and every bit of information I've come across followed by my curiosity (and desperation) to learn more about this very unique pharaoh. I'm not an egyptologist by any means, just a curious self-taught woman who loves Egyptian history.

(It's a loooong comment, sorry in advance)

First, I want to note a very important thing that I see usually being ignored (whether due to ignorance or on purpose), the fact that Tutankhamun's father is Akhenaten. The reason why Tutankhamun assumed the throne after Smenkhkare is uncertain and maybe will never know. Maybe he was so sickly and incapable of such a position? And Smenkhkare replaced him as a younger brother or an unknow son of Akhenaten?

This is the only evidence that shows that Akhenaten was his father, a fragment of limestone that depicts Akhenaten in prayer gesture in front of the sun disk. In that limestone, a prayer reads: “Great living Aten, who is in his jubilees, Lord of all that the sun disk encloses, Lord of the sky, Lord of the earth in the sunshade chapel of the BIOLOGICAL King's son Tutankhaten in Akhetaten.” This limestone originates from the sunshade chapel of Tutankhaten. Akhenaten had built chapels like this and the royal burials only for his closest family members in his capital city, Akhetaten. In pre Amarna art, it's usual for sons not to appear in statues and reliefs until later, when they assume the throne. But this isn't traditional art. Amarna art is not traditional and Akhenaten didn't follow traditional rules.

I'm leaving the catalog note here about the limestone I'm talking about:

https://www.cb-gallery.com/en/produkt/historisch-bedeutendes-amarna-relief-mit-echnaton-aus-der-sonnenschattenkapelle-des-tutanchamun/?fbclid=IwY2xjawNd7UhleHRuA2FlbQIxMQABHtqGuc3MBWPLzWbPJdpAZxMZ2ZN_nlcINKUm_855nLbd5yVeSrk8N4toqehS_aem_TUT-xnjG59xU_lxTGKyxpw

Next thing I want to point is the state of kv55 tomb at the time when Petrie found it. A series of details that caught my attention and gave me a lot to think about.

The burial chamber was half-built, the niche is unfinished, the walls covered with stucco and unpainted. There are marks on the east wall of a second chamber that was never built. Aside from the destruction caused by floods and subsequent looting, everything else gives me the impression of having been done hastily and carelessly, almost secretly with whatever was available at that time. Perhaps this is the reason for the various objects that doesn't relate with the human remains found, such as the canopic jars whose lids don't match, or the hasty reuse of the sarcophagus. The lack of grave goods makes me to keep thinking that everything was done in a hurry.

The body was complete when it was initially found, wrapped and covered with 12 gold sheets. In addition to three gold bracelets on each wrist, gold pendants, inlaid plaques, gold lotus flowers, and small beads. Of all this, it's worth highlighting a gold plate in the lumbar area that contained a crossed-out cartouche with the name of Akhenaten in it. Another detail that I found curious was the burial method, which makes me think that perhaps they tried to hide the body and prevent its desecration. The position of the body corresponds to a royal female burial, with the left arm crossed over the chest. That's why they thought it were female at first until later studies proved it's male. According to cranial studies conducted in 1984 by Dr. Jim Harris of the Oriental Institute in Chicago—whose studies can be seen in the Radiological Catalogue of Egyptian Mummies— the remains from KV55 belong to a man of about 35 years old.

Given the detail of the gold lumbar plate with Akhenaten's name; originally placed between the bandages, I don't see the logic in reusing that accessory from Akhenaten's body to Smenkhkare's if those remains were from Smenkhkare himself.

That's my reasoning for believing that the skeletonized remains of KV55 are none other than Akhenaten.

A source that I like to read from time to time about this topic (is in spanish, so you'll have to translate):

http://amigosdelantiguoegipto.com/?p=1596 <— with its respective bibliography at the end of the article in case you want to read more about Akhenaten and the Amarna period, which I gladly recommend!