I also very much doubt an outstation will be able to issue a boarding pass for another outstation with no connection in play without a lot of kerfuffle. If it is even possible it will no doubt require the supervisor/station manager to do it, and why should they distract themselves when the flight has nothing to do with their operations?

A data point - I tried to bag drop and get my QR boarding pass at FCO for the evening flight whilst the afternoon flight check in was open for check in and the J check in desks were not busy. Absolutely no dice even after checking with the FCO supervisor - they explained that their check in system wasn't flexible enough to permit them to handle my check-in for a later flight.