If you can draw a light weapon while grappled, you can draw stuff even smaller. Does say it requires winning a grapple check though, and if you've been swallowed you're likely going to lose just based on assumed size bonuses.
Now if the item is magically stored in, say, an extradimensional space via magic item, then drawing it is counted as part of the item's activation and activating magic items is allowed without a check.