The OEM is Motorola. The partnership was announced earlier this year.
You are correct about them not getting early access from Google. There was a post within the last few months saying that Google no longer releases a lot of the code via git, but instead requires submitting a form and downloading the code via Google Drive. Google are actively trying to make third-party development difficult.
We are told the OEM in question is not Motorola, and it's likely some benefits of the Mototola partnership aren't yet in effect due to silly bureaucracy. Not sure there is any reason to lie about this.
Embargoed ASB patches started being used in release 2025092500, but I can't find now the message where a Motorola employee (confirmed by a community moderator, spring-onion, in a Side of Burritos interview) first reached out publicly on the GrapheneOS Discord guild about how to obtain further technical guidance than the requirements list in the website which claims to be non-exhaustive, in order to confirm such message's date. Still, GrapheneOS claims (after the partnership announcement March this year) that ASB patches are provided by (effectively) a distinct undisclosed OEM, really meaning an employee is leaking them. Maybe even the person didn't disclose the OEM they work for but they must be associated to one in order to have access to this material.
