Please make a command so that if a gravestone can't be recovered an OP can return the items that a player lost on their last death, either in a gravestone next to the player, or straight into the player's inventory.
I'm not quite sure how to label this as a suggestion.

How do you use this command?

It's described either in in-game info book or FAQ.

Is it even me who is supposed to label it?

You can't label it as a suggestion, no. Someone on the team will label it
for you.

This seems like a nice idea though.

Looks like I implemented that one some time ago. Check /ob_inventory restore (described in info book)