It's hopeful news. GrapheneOS have had access to security patches as part of their agreement with an OEM partner already, so I assume these discussions/plans have been with the same partner. They are also hopeful of getting full access to AOSP releases which would greatly alleviate the pain Google have put custom OS developers through recently.

I am still very surprised that any OEM is willing to commit to monthly security updates and OS upgrades for a minimum of possibly five years. I think it would be a good thing for GrapheneOS to have more than one partnership in future for the Android ecosystem as a whole.