GrapheneOS I understand your comment fully, but I want to clarify. Are you saying that the option discussed here is enabled by default on GrapheneOS, making the Pixel 8 the first device supporting this both with GrapheneOS (even before the Google rom)? In the past this has not been enabled on any Pixel device, with or without GrapheneOS. Have you tested it (and could you potentially even post pics/screens)?
This is the one feature that has stopped me from purchasing newer Pixel devices, and I'd really like to know definitively whether displayport alt mode works.