Just do what I done. Platinum it on ps4 then platinum it on ps5. It's worth playing again on ps5, from the start. Not really any point in buying the ps5 version if you don't intend doing that.
So you can continue where you've got in each dlc and do new game+ in the main story. If you've completed any trophies previously they also apparently pop straight away on the remastered one
I would imagine you can upload as many as you want. Why would you want to though?