"it's OK to handwave pockets, backpacks, purses, etc.
Pockets? Sure. Please don't do this if you're unclothed, though. Just play along with the magic of inventory and don't pretend you have a pocket when you don't even have a stitch on.
Backpacks and purses? No, not OK.
We have wallets, briefcases and certain other kinds of carry-able/wearable containers for specific types of contents. And since those ones are coded, they can be stolen, opened, emptied, lost, et cetera.
A handwaved backpack is a cheat when you look at it from that point of view, and it is contrary to the RP where someone puts their coded wallet in their fake "purse" and then gets it lifted. It's pick pocketing, not pick pocketbooking.
For the same reason, don't make a purse prop from material and RP putting your stuff in it. If the prop gets stolen but the thief doesn't get they contents they saw you pretend to store in it, you've just abused @rule 1.E, Circumventing In-Game Code.