@xl0p THere is one FAQ that goes like this:
"Where can I play the Open Beta?
The Battlefield 2042 Open Beta is available to play on PC (via Origin, EA app, Steam, and Epic) and console (PlayStation 4 and PlayStation 5, Xbox One and Xbox Series X|S). Please note, PlayStation Plus is not needed to participate in the Open Beta, however, if you're playing on Xbox you will need to be an Xbox Live Gold subscriber."
I saw this FAQ a couple of days ago, it is still there. They haven't change it. So I think we will eventually get to play the beta via the EA app. But given that there is no link to download the beta(the webpage should've been auto-updated after the preload opens, so they knew there is no beta download for the EA app), there might be some issues with the EA app to deploy the beta. But I hope they just forgot about the EA app, and it just will be a simple client update for us to play the early access when it starts via the EA app.