İ can put things in my offhand but there is no offhand in Bedrock

So, in Bedrock Editon, there is no offhand but if we get a command block and enter the command that gives

evry entity in the game a totem of undying it gives evry entity a totem of undying. But if we erase totem_of_undying and write

cobblestone, carrot, diamond_sword etc. the command works and we can see the item in our “offhand”. İf it is a item, we can see it but if it is a block we cannot see it but if we open our inventory, in the slot for the sheald and the totem of undying, it is there it dosent matter if it is a item or a block it is in the slot.