I have a Pixel 9 Pro XL with GrapheneOS, and a 2012 Ford Focus Titanium which has the Ford SYNC 1 system. The Bluetooth fails to pair every time, around 30 seconds after entering the 4-digit code displayed on the cars screen. An iPhone and a stock Android phone managed to pair instantly, so this must be specific to GrapheneOS.
I would imagine due to the cars age it uses an older, less secure, standard of Bluetooth that is disabled in GrapheneOS by default. Does anyone know how I can figure that out?
Edit: Bluetooth works with other (newer) devices, never had any issues at all, so it's not hardware I don't think. I've also already tried disabling Bluetooth A2DP hardware offload in developer options (I don't actually know what this is, I just saw it suggested somewhere) and rebooting but that made no difference.