@CFA I did not mean to criticize, just added the link so others could see (that the focus was more general over there).
On your original question here, @aibd and @Ptit-g have already posted valuable information that I won’t duplicate. Just adding here that if you depend on an OTA upgrade (i.e. via your phone’s Updater) to Android 15, you will need to wait a couple of weeks more:
As to what comes after that, I agree with @aibd that it is an open question if Murena will be able to bring Android 16 to the FP3. Right now, this has neither been confirmed nor ruled out by Murena. Just a few weeks ago, I was becoming more and more sceptical that A16 would make it onto the FP3 – but then I noticed the following topic and was able to install that (non-/e/OS) build on an FP3 myself: Android 16 with gapps for Fairphone FP3(+) (Treble GSI) - Development - Fairphone Community Forum
So we can just wait and see if Android 16 /e/OS for the FP3 will come or be declared not viable.