RF triangulation exists but requires either law enforcement + carrier cooperation or specialized equipment you probably don't have.
GrapheneOS doesn't include Find My Device because that's Google's surveillance infrastructure. No backdoor location tracking—that's the whole point. Privacy has trade-offs.
The good news in this case: GrapheneOS or not, if the radios are on, the phone is transmitting.
Your phone is still transmitting even when idle:
- Cell tower pings every few seconds (network registration)
- IMEI/IMSI broadcasts during those pings
- WiFi keepalive packets if connected
- Bluetooth advertisements if enabled
- Background RF noise from oscillators and processors
If the phone is nearby, here are some things to try:
If you've got WiFi on and it's connected to your network, check your router admin panel for connected devices. You can also use arp -a or ip neigh to see if it shows up on your local network, or try pinging it.
Bluetooth on? Use a BT scanner app on another device. Walk around and watch the signal strength. Range is about 30 feet. I've found lost earbuds this way.
Hope this helps!