It is quite disappointing Jolla finally decided to take this stance.
From the minutes (#sailfishos-meeting: Sailfish OS, open source, collaboration -- 17th December 2020):
- Official decision to publish C++ part of Silica under LGPL has unfortunately not been made. We will clean up the headers. (sledges, 09:05:37)
- https://www.gnu.org/licenses/gpl-faq.html#SystemLibraryException (ViGe, 09:09:33)
- https://www.gnu.org/licenses/gpl-faq.en.html#WindowsRuntimeAndGPL (piggz, 09:22:30)
From the GNU FAQ:
It is possible to write free programs that only run on Windows, but it is not a good idea. These programs would be “trapped” by Windows, and therefore contribute zero to the Free World.
What @rinigus and @piggz mentioned above is probably the best way out, but I’m afraid this means too much work for most small one-person projects - i.e. probably almost all Sailfish apps. 