The Abhidhamma is a different presentation of what is in the suttas, in fact the two pitakas are known as the ultimate and conventional views of the teaching respectively. There are many references to C&U reality in the suttas as underlying concepts.
In the well known example of the chariot ultimate reality is implied:
Sister Vajira: “Just as, with an assemblage of parts,
The word ‘chariot’ is used,
So, when the aggregates are present,
There’s the convention 'a being.”—-SN 5.10
"Citta, these are the world’s designations, the world’s expressions, the world’s ways of speaking, the world’s descriptions, with which the Tathagata expresses himself but without grasping to them.”—DN 9
"Now, if there are any who ask, ‘Would there be the right contemplation of dualities in yet another way?’ they should be told, ‘There would.’ ‘How would that be?’ ‘Whatever is considered as “This is true” by the world with its devas, Maras, & Brahmas, with its contemplatives & brahmans, its royalty & commonfolk, is rightly seen as it actually is with right discernment by the noble ones as “This is false”’: this is one contemplation.
‘Whatever is considered as “This is false” by the world with its devas, Maras, & Brahmas, with its contemplatives & brahmans, its royalty & commonfolk, is rightly seen as it actually is with right discernment by the noble ones as “This is true”’: this is a second contemplation. For a monk rightly contemplating this duality in this way — heedful, ardent, & resolute — one of two fruits can be expected: either gnosis right here & now, or — if there be any remnant of clinging-sustenance — non-return.”—-Sn 3.12, ‘Contemplation of Dualities’.
Practitioners experience bare awareness momentarily but then don’t know how to extend it and at that stage are like Adam and Eve in the garden before they sinned. There is only one way to extend bare awareness and that is by reducing and overcoming the hindrances so they don’t arise as sense impressions arrive. But overcoming the hindrances means recognizing two types of thought (MN 19) and they baulk at this because it involves dualities and they are used to the single thinking of bare awareness or subject to a remnant of xtian conditioning. However the difference between Buddhism and Christianity is that in Buddhism there is no saviour, the practitioner has to save themselves and are given the means to do it through the instructions on removing the hindrances. So to progress from bare awareness it is necessary to enter into duality armed with the weapons of the dhamma.