I develop for SailfishOS. As I described in one of my other comments, it really is just "regular" GNU/Linux underneath:

>> I develop software for SailfishOS. It's like the Linux desktop. I SSH into my phone. zypper/pkcon install some dev tools (e.g. gcc, make, git). I initialise a Python virtualenv, pull down some libraries (e.g. Flask). I want to query SMS messages? I open an sqlite database on the filesystem. I can define services using systemd files. It really is "just Linux" underneath.