On a related note, you can redistribute DNS66 binaries without source code, as the binaries include a link to their source code and the copyright statement.
The copyright statement in the "About" screen is NOT an "appropriate legal notice" as defined by the GPL and might hence be omitted.
Other copyright statements and license are distributed with the apk, but they're not visible, as they are a text file inside the apk (which is a zip archive really).
Note that copyright law might still require you to preserve the copyright notices, I don't know.
Server run by the main developers of the project It is not focused on any particular niche interest - everyone is welcome as long as you follow our code of conduct!