Based on numerous posts I have read came to conclusion that GrapheneOS would not be fully secure on anything but pixel phones.

Based on developers/member of community’s knowledge, why is this the case, why has the google pixel phone been the designated device(s) chosen to accommodate GrapheneOS? Why not Samsung?

nrt Well understood, but Pixels are financially inaccessible for most people due to import charges. The project would get a better reach if support could be extended to higher end models of other smartphone brands.

I just don't see the project team deciding to support unsuitable hardware just to get a bigger market share.

    Basically: Graphene os is super secure because its custom built for a specific device. The google pixel was choosen bc it has a very rare chip(The Titan M/M2 chip) with very special funtions. The pixel is just the best and supporting other devices wont be as fruitfull as a pixel device.
    Graphene is for maximum security, not support.

    nrt Does this mean that the hardware of the device as to be secure enough in the first place?

    If hardware is important when it comes to security, what hardware advantages does the Pixel phone have over Samsung S series (or Samsung hardware vulnerabilities) that allow the Pixel to be the best candidate?

    You were given an answer above, please read this carefully: https://grapheneos.org/faq#future-devices

    A proper candidate must have a properly configured SoC with decent firmware support and proper support for alternative operating systems. It also must have a secure element to make use of the Weaver/StrongBox APIs on Android (Google has Titan M, some of the Samsung flagships have one, and there's also the Qualcomm SPU). Not all SoCs/secure elements are equals when it comes to hardening and Pixels generally have the upper hand (for instance, Titan M has insider attack resistance, meaning its own firmware can't be updated unless some conditions are met).

    While modern Samsung flagships may have a secure element, they don't have proper support for alternative operating systems. In other words, they wouldn't allow verified boot to function correctly with a custom operating system - and Knox is known to be a terrible hindrance to that.

    You could say Google Pixels are the de facto standard for Android security and alternative Android-based operating systems support, and they don't cheap out where other OEMs do, making them the obvious choice for a security-focused operating system.