HMD, perhaps only second to Google in terms of software updates, has failed to release kernel sources for any of its devices so far. Users are also stuck with locked bootloaders, which makes any attempts at community support futile.
https://www.notebookcheck.net/A-year-after-launching-its-first-device-HMD-is-yet-to-release-kernel-sources-for-any-of-its-smartphones.282890.0.html