I don't understand, is that method not good / fast enough? The ubus call onion wifi-scan "{'device':'ra0'}" command will scan and dump the RSSI value of every AP in range in dBm.

root@Omega-C465:~# ubus call onion wifi-scan "{'device':'ra0'}" { "results": [ { "channel": "1", "ssid": "XXXXXXXXXXXX", "bssid": "YYYYYYYYYYY", "cipher": "AES", "encryptionString": "WPA1PSKWPA2PSK", "encryption": "psk2", "signalStrength": "0", "wirelessMode": "11b\/g\/n", "ext-ch": "ABOVE", "rssi": "-93" },...