people don't even try to understand what the others are trying to say
I think that's very uncharitable, especially because you seem to have misread the thread yourself. Note: I don't say "people don't even try to understand [...]", because my charitable reading is that you misunderstood one of the comments (comment 2) and therefore the whole thread. My reading of this thread:
1. chrysoprace prefers GrapheneOS (over PixelOS)
2. jnkl says (paraphrased) "great, how are you going to run GrapheneOS if you don't have a Pixel?", this submission about PixelOS, which works on non-Pixel phones.
3. hurfdurf reacts by pointing out the Motorola Signature, will soon be available. Which is a counterpoint to (2), namely that GrapheneOS (soon) works on non-Pixel phones.
4. nicce circles back to the wide phone support of PixelOS by pointing out that GrapheneOS is still limited to Pixels and one Motorola model (which is still very limited, extending the argument of (2)).
5. microtonal (me) points out that this may be true, but GrapheneOS has requirements that make it impossible to go beyond these phones (implicit: yes, for the rest you need to use something else)
Note that my reading of (2) is different and in my reading of (2) the whole chain makes sense and is consistent.