
So... this card reminds me very much of Preposterous Sketches, a card that is honestly pretty mediocre. The simple reality is that paying 2 resources and an action to draw three cards isn't economically viable in a game that is essentially about action management.
However, this card has one two major upsides over Sketches. The first one is that it cannot find weaknesses. This is actually a bigger deal than it seems at first glance since weaknesses are a major reason not to aggressively draw cards.
The second reason is the selection. You don't play backpack in any deck, you play it in a deck that has multiple Item or Supply cards that you really need. Here is a list of all Item and Supply cards.
While it could hit Emergency Cache (and is probably nice if it does hit at least one), you are really looking for decks that run a large number of qualifying cards. Mathematically, you want half your deck to be Item/Supply cards (probably more so you don't miss). Because that's the problem with this card: if you don't get three cards under it, it's really quite mediocre.
That being said, if you ever get Lightning Gun, Extra Ammunition and Emergency Cache on this thing... that's pretty good.
However, because it also takes up a body slot (not the most contested, but not trivial either), I don't see this card getting a ton of play. So, better than Sketches in a few decks, but probably still not the Diesel we need.