We allegedly do 2 things as Early Access Players:
1.) Play the game where we encounter bugs and automatically generate user statistics. I don't think this merits any reward, as its completely offset by the opportunity to play the game early. A single thank you would be fine, but I'm sure somewhere Larian has already thanked us for doing this.

2.) Provide feedback through the official BG3 reporter, these forums, and/or reddit. To be honest, at this point I'd be more angry than appreciative if Larian explicitly thanked or rewarded us for doing this. I believe they've mentioned the forums once, saying that they had dozens of pages of feedback from reddit+the forums in their December patch video. However, they haven't actually responded to or even mentioned specific topics here. Why are they using the chain mechanic? What are their thoughts on how Larianisms such as dipping, high ground advantage, and surfaces affect the gameplay? Do they realize that the previous reasons are why Bless isn't that useful, or do they still think that "players only like flashy abilities"?
I'd feel patronized if we were given a reward for providing feedback, given that it doesn't feel like Larian has actually considered any of this feedback.

tl:dr: The reward for EA should be participating in EA, which at the very least should include an acknowledgement from Larian of the specific topics we've brought up and hopefully their reasons for or for not implementing them. Otherwise, just call us bug testers.