I started working on it. I have a small demo app (really rough : https://github.com/Gnu-Bricoleur/Kompass).
There's two major issues right now :

• Increasing the sampling speed of the magnetometer requires admin rights
• The magnetometer values seems to be nonlinear and simply spinning the phone is not enough to asses it without knowing the true value is not enough to calibrate it (still working on that)

Is it OK if I claim this project ?

Yes it's fine :) Thanks for looking into it!

I have a POC available at this address : Kompass
The compiled binary :

Cool, thank you for working on it! For the next steps, consider moving the repository to invent.
I have a few comments on the code, but I'll just open a merge request once it's on invent :)

It's on invent, on this repository
Thanks for your interest !

Thanks, I have done a few commits, is it okay if I do one bulk merge request? The changes are separated into commits.

Sure, Thanks a lot for your help !

I also made a small MR :) https://invent.kde.org/smigaud/kompass/-/merge_requests/2

btw could you add a license file to Kompass? even better make it reuse compliant :)

Randome drive-by comment: Would it make sense to use https://doc.qt.io/qt-5/qcompass.html ?

In T8905#258273, @ognarb wrote:

I also made a small MR :) https://invent.kde.org/smigaud/kompass/-/merge_requests/2

btw could you add a license file to Kompass? even better make it reuse compliant :)

Thanks, it looks great, I'll merge it tomorrow.
I've never done an appstream file, thanks for taking care of it!
Why did you add a BSD close to the makefile ?
I'll make sure to add a global license file!

In T8905#258274, @nicolasfella wrote:

Randome drive-by comment: Would it make sense to use https://doc.qt.io/qt-5/qcompass.html ?

Sounds interesting ! I even found an exemple

Why did you add a BSD close to the makefile ?

We usually track the license of each file separately using the SPDX identifiers, to make code easily reusable across repositories. A GPLv2+ file could be re-used by a GPLv3 project, but it would be incorrect to just relicense the file as GPLv3.

All of the options are documented in the licensing policy: https://community.kde.org/Policies/Licensing_Policy
I don't know for sure why the licensing policy states to use BSD for cmake code, but I suppose it's to make it easy to move code to extra-cmake-modules, KDE's collection of useful reusable CMake code. extra-cmake-modules itself is under BSD so code can be moved into CMake itself.