Does the box mention Ryzen 5000 support? If so, no worries. Otherwise, you are going to need any of the chips only needing the F1 bios revision to work.
I'd call around to local computer repair shops and see if any of them can flash the BIOS for you...it will be cheaper (hopefully) than buying a cpu you dont need.
It seems they are doing it for B550 boards, not sure if they are still support older B450 boards. But they should, you bought the CPU at least recently.
Any 1st/2nd/3rd gen cpu will do.
You can go to your local tech service and ask them if they have a 1st/2nd/3rd gen, and ask them to do the BIOS update for you.
Surprised AMD just isn't insisting they put CPUless flashing capability on all the boards, or bake it into the chipset. They should have seen this coming after the last time.