As one of the developers behind the cadet-gtk application I wanted to add that there’s no additional funding needed. The application was only a prototype and has been discontinued.
However it will get replaced by the more polished messenger-gtk application running on mobile Linux as well as desktop. You can find more current information about it here. It has also been accepted to be funded by NLnet (more information here).
But I’m also looking forward to optimize other applications from GNUnet for mobile as well.