rsm if you have your settings in GrapheneOS such that the phone cannot scan for nearby devices, that goes both ways, and that other devices cannot scan for your phone
I don't think it's both ways. If you have your Bluetooth radio turned on, it can be scanned.
If you don't want to be tracked (stores, state surveillance, etc.) your radios must be off. Tracking GSM, LTE and other cellular devices can still be done, but the equipment is expensive.