A Titan-M-chip in a future Fairphone model would actually be a great thing. Then GrapheneOS would be possible, which is currently probably the most secure and privacy-friendly custom ROM under Android. However, you would have the dilemma that there are no security updates at all after 2-3 years. Graphene only supports a device as long as there are kernel and baseband updates. Thus, the Fairphone would be electronic waste at an early stage. This contradicts the idea of using a Fairphone (or other smartphone) as long as possible for the sake of the environment. Everyone has to make this decision for themselves: Does the environment come first or my personal IT security and data protection? With other custom roms, you at least get the security updates for the OS even without the urgently needed kernel and baseband updates. In the long run, there is only one solution: There has to be a way to update the kernel and baseband for as long as you want. But whether this problem will ever be solved without Qualcomm and Co. (and they of course have no interest in it) ??? Unfortunately, we are currently still far away from being able to operate a smartphone “safely” for many many years.
After all, the EU seems to want to tackle a law with which there should be an obligation that a smartphone must get all security updates for at least 5 years. That would at least be a first ray of hope…