its been confirmed that Steam EA players get the upgrade... other platforms are mostly assumed to also get it
From lates BG3 update, in which the deluxe edition and free upgrade were announced:
Do you already own Baldur’s Gate 3 on PC? Are you planning to purchase it in Early Access before launch? You’re going to get a free upgrade to the Digital Deluxe edition on launch day! Same goes for owners of our Collector’s Edition
