Hmmm let's see.
The Absolute, we do know that consists of an entity at the top of the Ranks (I'm going to guess Vecna, we can certainly discuss that), and right below, is what I consider to be the new incarnations of the Dead Three, I think Myrkull's incarnation is the female pale elf communing with the Goblin priestess trying to read you. Since the Absolute is responsible for the "true souls" creation, they'd need a tadpole supply, hence an Ilithid colony. Now, as we see in the very first trailer, Baldur's gate is ravaged, what seems to be the aftermath of our ship's invasion, yet we witness a rapid case of ceromorphosis, which means the same tech used in our Nautiloid through Avernus.
https://prnt.sc/rvUCmVULFC3ZAt the very start of the trailer we see prominent the mark of the Absolute on Baldurian city walls which either means it got marked by the second wave attack, or the Absolute has been long operating in Baldur's Gate under the guise of the Dead Three cults, or both? Now as we see at the end the city seems to have been visited right after the first attack by other mind flayers employing a faster? version of the tampered tadpoles as we see the Ilithid levitating up the sky revealing another working Nautiloid and an army of freshly made Ilithid.
Now I have to kinda agree with you that the Ilithid inserting us the tadpoles might be a double agent, thinking an agent of Shar, as I feel like she is trying to destroy the Absolute. We know for a fact that the tadpoles in our brains are tampered with Shadow Magic, specifically Netherese. Now that's a very specific stench. The Shadow Weave is only accessible through worshipping Shar, and as Sharran worship was the state religion of the empire of Netheril, we can safely confirm the tampering of our tadpoles is to her knowing.
