How can I get a stable version of the Fairphone 3 OS source code

[yvmuell]

Hi and welcome, I have no clue, maybe this helps

Fairphone 3: Android 11 Proprietary Blobs preview package

We are happy to announce that we have publicly released a preview package of Android 11 proprietary blobs. You can download the blobs package from Fairphone 3 Additional Downloads section on code.fairphone.com. This is just a preview package which includes all necessary modules for basic functionality. However, the final version will be available post public release of Android 11 on Fairphone 3. Please feel free to discuss this release in this category of our forum!

Fairphone 3: Android 11 public source release

Dear all, Transparency and openness are at the core of our ambitions to bring more fairness into our products – and also into the software on our products. Following this ambition, we’re excited to announce that we are publishing the source code of Fairphone 3 Android 11. You can find instructions to download the source tree and to build your own Fairphone 3 software on code.fairphone.com. If you are interested, you can also send patches and contributions to our Gerrit instance at https://gerr…

Else maybe check the Lineago OS instructions on how to build…

https://wiki.lineageos.org/devices/FP3/build