[OnePlus 7 Pro Guides, News, & Discussion] twinnfamous:
While going through some things I came across this

<?xml version="1.0" encoding="UTF-8"?>
<filter-conf>
<!-- *#808# -->
<!--
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.EngineerModeMain" />
-->
<!-- *#36446337# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.EngineeringMode" />
<!-- *#8778# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.manualtest.MasterClear" />
<!-- *#806# -->
<!--
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.autoaging.AutoAgingMainListActivity" />
-->
<!-- *##*37847# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.manualtest.DeviceListActivity" />
<!-- *#*#7668#*#* -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.manualtest.CheckRootStatusActivity" />
<!-- *#807# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.autotest.AutoTest" />
<!-- *#805# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.bluetoothtest.BluetoothTest" />
<!-- *#804# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.NetworkSearch" />
<!-- *#803# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.wifitest.WifiSettings" />
<!-- *#802# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.gps.GpsActivity" />
<!-- *#99# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.KeepSrceenOn" />
<!-- *#6776# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.CheckSoftwareInfo" />
<!-- *#888# -->
<!--
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.PcbShow" />
-->
<!-- *#809# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.echotest.EchoTest" />
<!-- *##*8110# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.qualcomm.OtaSwitch" />
<!-- *#801# -->
<!--
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.qualcomm.DiagEnabled" />
-->
<!-- *#008# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.LanguageSwitchToChineseActivity" />
<!-- *#67760044# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.LanguageSwitchToEnglishActivity" />
<!-- *#268# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.qualcomm.QualCommActivity" />
<!-- *#900# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.BackCameraAdjusting" />
<!-- *#911# -->
<!--<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.PowerOff" />-->
<!-- *#10000# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.MarkResultShow" />
<!-- *#814# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.TDSNetworkSearch" />
<!-- *#824# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.WCDMANetworkSearch" />
<!-- *#834# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.LTENetworkSearch" />
<!-- *#818# *#838# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.NetworkSearch_New" />
<!-- *#928# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.wifitest.WifiFTMActivity" />
<!-- *#8019# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.wifitest.WifiSocketHelper" />
<!-- *#7332# -->
<activity packageName="com.oem.rftoolkit" className="com.oem.rftoolkit.RfToolkitFactory" />
<!-- *#7328# -->
<activity packageName="com.oem.rftoolkit" className="com.oem.rftoolkit.RfToolkitAgingTest" />
<!-- *#7327# -->
<activity packageName="com.oem.rftoolkit" className="com.oem.rftoolkit.RfToolkitCustomerService" />
<!-- fingerprint calibration -->
<activity packageName="com.fingerprints.fingerprintsensortest" className="com.fingerprints.fingerprintsensortest.FUNFingerPrintCalibrationTest" />
<!-- *#806# result page -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.pt.PtActivity" />
<!-- fingerprint calibration result -->
<activity packageName="com.fingerprints.fingerprintsensortest" className="com.fingerprints.fingerprintsensortest.FTFingerPrintCalibrationResult" />
<!-- *#899# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.aftersale.ChooseBackCoverColor" />
<!-- *#845# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.wifitest.WifiApSettings" />
<!-- *#*#866#*#* -->
<activity packageName="com.example.tmo" className="com.example.tmo.TmoActivityList" />
<!-- *#8020# -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.wifitest.WifiAdbHelper" />
<!-- fingerprint calibration -->
<activity packageName="com.fingerprints.fingerprintsensortest" className="com.fingerprints.fingerprintsensortest.FTFingerPrintCalibrationTest" />
<!-- front camera motor and hall calibration -->
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.manualtest.motor.MotorHallAfterSaleCalibration" />
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.manualtest.motor.MotorHallCalibrateActivity" />
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.manualtest.motor.MotorHallForceMove" />
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.manualtest.motor.MotorHallSelfTest" />
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.manualtest.motor.MotorStepHallCalibration" />
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.manualtest.motor.MotorStepTest" />
<activity packageName="com.oneplus.factorymode" className="com.oneplus.factorymode.manualtest.motor.MotorTestActivity" />
</filter-conf>

This file was taken from T-Mobile GM1915

Please be careful what you do as I'm just posting a find. I have not tested.

So the risk is on you.