Yep, GOOlocks usually have Cthulhu, Hastur and Dendar, seeing as Illithids aren't part of the equation when it comes to GOOlocks in D&D.
None of whom are likely to be in BG3. So, it will be some other being associated with the Far Realm. Note that there is no reason to suppose the patron is anything like god-level power, Wyll's patron is only a cambion.
