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.

I had never heard of SailfishOS before this thread. Now I really want to pick up a device with SailfishOS, but I was planning on getting on GoogleFI compatible device in the next couple months. Decisions...

In any case, thank you for your efforts. I've been waiting for UbuntuOS for all the features I didn't know Sailfish has already.

How much of SailfishOS is covered by GPL or GPL compatible license? I don't want to invest my time into someone else business for free.