HiFiBerryOS is an open source distribution and we're happy to include distributions from users.
Ease-of-use is the main goal of HiFiBerryOS. We don't want to create another distribution with hundreds of settings that most users don't understand. That also means, we might just not implement something if we feel that it is hard to understand or hard to use for end users.
The best way to integrate features is fully automatic without the user having to configure something. We know that this isn't always possible, but try to think about what settings are really needed for users. Don't add any settings that 90% of the users don't need and/or understand. Feel free to let expert users edit configuration files with settings that are rarely used
You extension must be able to work with all supported HiFiBerry sound cards. This means that it needs to be able to handle all common sample rates (44.1-192kHz) and sample formats (at least S11_LE, S24_LE, S32_LE)
Every music service need to report the status via MPRIS. It needs to support at least the "STOP" command.
We recommend to contact us at support@hifiberry.com before working on a new module. We might be able to give you some tips to make sure, your contribution will be accepted once your work is done.