And you can help making it accessible to more GNU/Linux users!
We have decided not to create a Replicant 6.0 SDK as part of the upcoming Replicant 6.0 release. For three previous Replicant versions (2.2, 4.0 and 4.2), a SDK was provided.
Replicant offered its own SDK because the Android SDK released by Google is distributed under a non-free license and suggests installing non-free plug-ins such as the Google APIs. For a long time, Replicant has provided the only Android SDK that is available under a free license and that doesn’t offer to install non-free software.
Android SDK in Debian
However, for some time, the Android SDK is available in Debian and it will be possible to build Android apps in Debian Stretch, the upcoming release. The Debian packages suffice to build an app that only has a minimal set of dependencies. Not all libraries that might be needed for building an app are already packaged, but it seems that nothing is missing that would otherwise be available in a Replicant SDK. The packaged Android SDK in Stretch even has the same target API as a Replicant 6.0 SDK would have.
The packaged Android SDK in Debian has many advantages over a Replicant SDK. Build tools should be installable from the package manager of the distribution you are using and not be distributed in a binary archive outside of it. Android SDK packages are provided in Debian alongside other Android build tools like Gradle. The packages can be built reproducibly. We only have very limited time and resources to work on the SDK. Debian has its own team, the Debian Android Tools team, that focuses on packaging more libraries and target APIs, among other things.
Packaging for more distributions
For these reasons, rather than spending time and development efforts on a Replicant 6.0 SDK, we encourage you to work with maintainers to get the Debian Android packages included in more distributions. As Replicant itself is a fully free software distribution, we would be especially happy to see the packages included in fully-free GNU/Linux distributions, like Parabola or Trisquel.
The Debian Android Tools team is available to answer questions and they are interested in having cross-distro collaboration to solve remaining issues. They can be reached via their mailing list or in the IRC channel #debian-mobile. Their wiki page provides useful documentation.
Of course, we are available as well to answer questions and to coordinate these efforts.