We can use one of the two drives or both that operate based on rpm and fuel flow to turn on a relay that is normally connecting the signal line from the O2 to the link and switch it to a constant voltage of anywhere from 0-1v based on which voltage is easiest to create. Set the lambda target to this voltage. This way depending on your setting and if it is connected to both drives the ecu will go into open loop at a certain rpm and/or fuel flow.
My other idea (less likely to work):
If we can compress the wideband voltage into 0-1v then we can use it since we can set whatever lambda targets we want (0-1v). From the other posts I've read the resistance of the wideband sensor doest do much and is there just to check the condition of the sensor every once in a while. So all it would take is a device that converts the 0-5v of the wideband with a ratio of 1/5 into a 0-1v. Seem possible?