I know, that this subject was mentioned a number of times before, but I didn't know where to write it.
Recently on a Polish facebook page of WiMP someone asked when they will add support for Liunx. They replied, that there are no plans for official Linux app. So I asked if they will ever share their API for others to implement WiMP in systems like Runeaudio or Volumio.
Today they replied, saying that right now they do not share it (like it was some kind of a news ), but it is possible that they will in the future.
Nothing specific, but at least we know, that there is a light at the end of a tunnel