I don't think you would be able to transfer a save file for a farm on ps4/5 to another ps4/5 that is not of the same account ,You might be able to use a flash drive If your friend is nearby ?? It hurts a bit to lose a file, It sucks to have others lose interest I know how that feels too.. My ps4 hard drive crashed in 2020.. and because I didn't cloud save often I lost 3in game years of progress on my now 21 year old farm.. but I enjoy Stardew It took me a while but I built it back better.. How much progress did you lose ?? I enjoy the co-op too, If you are an adult looking for chill adult people to play with I don't mind being a farm hand.. either way I'm sure you can build it back better.. Sorry not much help with the transfer host problem. Most players here seem geared towards switch and PC.. It might take a couple days but someone who knows for sure might chime in with a better answer. Best of luck :)