My understanding is that Jared has played an integral role in helping get so many Muslim countries to build ties with Israel.
I highly doubt he would want to see his hard work be for naught when a Biden Administration dismantles what he has helped build.
To the extent that Jared had conversations with his FIL about conceding, I believe these conversations consisted of giving Trump advice on strengthening his arguments about election fraud so that he can hold out on conceding.
Believe you are the winner of this thread. There were likely a number of things discussed and the idea of how and when to concede, if it were ever determined to be that only realistic option, probably was mentioned in that sort of context.