I also wonder how we convert the early access game in Steam into the full version (digital deluxe version). I heard Larian speaking about some codes being released that we can use.
It's also strange that Steam only has the early access version available and not the collectors editor or digital deluxe version. At the moment it seems the digital deluxe version is only available to purchase for PS 5 players. So I expect Steam has quite a lot of work to do around PC release time to make it possible to purchase all versions of BG 3.
We do indeed need clarity from Larian, but hopefully I can offer at least an educated guess on these two points.
The Steam codes you've seen mention of, I believe, are those for the Collector's Edition, which is purchased directly from Larian and doesn't come with a code that someone can use to play now. Originally, the digital download codes for CEs were going to be on (or in?) the physical boxes, but as it seems those aren't going to be ready to send until later in August, Larian have now decided to email them so CE purchasers can start playing the full game as soon as it releases.
The CE isn't available on Steam as it is mainly a physical thing, and so needs to be ordered from Larian. The actual version of the game it comes with is still digital, and I believe the only different in game content is a CE-specific dice skin. Everything else seems to be the same as the Digital Deluxe.
And the reason you can't buy a Digital Deluxe edition separately on Steam is because
every game bought at the moment will be Digital Deluxe, as everyone buying early access gets a free upgrade. I guess we'll see for certain soon, but I'm now guessing that what this is going to mean is that everyone buying the game up some point (possibly 2 August) will get the Digital Deluxe edition for a normal edition price, and then at some point (maybe not until 3 August) two versions will be made available so that everyone just paying the early access price will get the base game, and people will have to pay extra to get the Digital Deluxe bonus content.
