Again, those aren't tie ins, they are synergistic. A tie in would actually say "Badlur's Gate 3" on the cover, and as with Honor Among thieves, WotC seems to be pointedly avoiding that. There is probably a good business reason i don't understand, but it feels like a lost opportunity.They are. They have been plugging Decent to Avernus based on BG3, and the new Phandelver Campaign. "look, Forgotten Realms! Mind Flayers!!"
To expound: a tie in would have been a reissue of Avernus with a new cover that says "The Prequel to the Hit CRPG Baldur's Gate 3!" or somesuch.