On the signup screen after email confirmation there are 3 fields: Display name, Username and Password
It's impossible to update the display name and the password at the same time (I'm not sure if it's a local check or an API limitation).

Is there any way to reproduce this behavior with a development build?
I'm asking this because the OAuth2 Authentication section of the README states that:
credentials created with our WordPress.com applications manager allow login only and not signup
Edit: Just thought of a naive way of doing that: starting the signup using a production version of the app and then opening up the "magic link" in a second device using a development version of the app. This is not practical at all, but I'm gonna give it shot later and see if it works. Either way, I'm still open for other suggestions.
Edit 2: After looking into the code I figured I can just force the app to show the SignupEpilogueActivity after initialization. That should help with debugging for now.
Edit 3: @maxme just provided me some OAuth credentials that I can use to test the signup flow.
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