Minecraft Items De spawning

probably the items are in the surface, generally when items are inside blocks they tend to go up, for example in item elevators before the update aquatic, so try to get to the surface or in any cave above ur death sopt

Ps4 encrypts its save files and requires them to have been encrypted via a PS4 to read them back, so sadly, you will not be able to transfer files directly from iPad/PC/Android.

You can transfer them via realms (though this will require you have PSplus on your psn account) now that PS4 finally supports them. Setup a Microsoft account and link it to the PS4 account you use (this is a one time operation so make sure you link the proper Microsoft account to the proper psn account). Buy a realm and then upload your save to your realm from your iPad using the same Microsoft account. You can then download the realm save on the PS4.