Thank you very much for your answers. I also tried to follow the technical details in the above mentioned thread but read it only roughly. As a non-expert it is really very hard for me.
If even the experts among you constantly get stuck somewhere … a non-expert just takes too long to acquire this knowledge. Example: I only imagine what a boot.img is, I have no idea how “special” it is for a certain purpose and certainly not where I get it and who creates it. Does it have to match the device or the Android version or both? Are there risky sources etc…?
There are dozens of hurdles for a non-expert to jump over.
There needs to be a tutorial that explains everything, I mean really everything step by step so that no one gets stuck anywhere, even things you guys here in the forum take for obvious. I would offer myself, as a technophile but half-knowing user such a tutorial to co-work if I find someone here, I may annoy with all the questions about how, why and why not otherwise etc… The goal should be that someone like me has the complete information to safely perform the necessary procedure.
Meanwhile I had contact to the fairphone support and asked to bring my request (FP4 prepared for signature spoofing without root) to the attention of product management:
“For a product to be fair, it must not only be fairly produced, but also fairly used. This also means being able to handle your data in a self-determined way, which is practically impossible due to Google’s dominance. In my opinion, a fair smartphone must be able to be used by normal consumers without Google (without knowing a specialist). I am convinced that with this possibility they will be able to win many more customers and spread the idea of the fairphone even better.”