Ah, no, I forgot this does exist, in fact I think it pre-dated Notion’s implementation. You just have to use # to create, rather than + or /. In other words #name of new entity, then select a type, and you can create in-line just like Notion. @B_Sp that’s what you’re looking for, right?
That said it doesn’t work fully with the keyboard, so that part could be improved.