My personal preference is to simply have all pickup items owned and spawned by the server. Have them set to replicate. Player Interaction RPC server to do a line trace from player cam. If it hits on the server, then the server handles inventory. validate item, quantity/capacity etc. Then it destroys the actor. No multicasting needed.
For physical items like swords, guns etc the server can destroy the simple sm variant and spawn…attach the sk variant. Again the actor reps and reps movement. Ownership is then set to the controller or pawn.
