Opening GUI when interacting with Mob holding item

I'm trying to make it so when a player interacts with an Allay who was given a Crafting Table it opens up the crafting table GUI, unless the player's hand is empty.
Also Shulker Boxes, though I think Crafting GUI is of higher priority for my concept (and that functionality sounds fairly more above-my-level-of-what-I'd-understand).
So far I've been scouring other data packs to see how they handle similar but I've found little in terms of presenting an interface upon interaction so, aside from pack.mcmeta, I've kinda been lost here.