Andromxda I'm not sure whether I should share the source, it's semi-public information. AFAIK official GrapheneOS accounts have so far avoided mentioning the name of the OEM, so I'm hesitant to share it. But I can tell you that much: It's not Nokia.
I suspect that anybody who actually knows also knows how important it is to keep quiet, to avoid possibly disrupting the negotiations. And I suspect responsible parties in the know are also aware of the dangers of "Well, I'll say it's not so-and-so".
I would hope that people who want to help the project would be able to figure out when helping the project means keeping quiet.
Please note that I do not speak for the GrapheneOS project.