I second the suggestion of the T.H.E.® Wallet from SpecOpsBrand.
Great quality, holds a LOT, and NO VELCRO(!!!), but still locks closed.
I usually have a Fresnel lens, led fishing lure light, a minisaw, and a rasorknife in mine.
It has a zipper security pocket in it, but I usually use it to hold my cash, because the main cash compartment is sized to fit European money and so is WAY oversized for American money.
You could probably carry one of the smaller survival blankets in the main compartment, if you refolded it to fit. The new AMK ones would probably be thin enough that you would not even notice it.
I wish they would make a new version where the BIG compartment zipped!
It is big enough to hold a passport book unfolded in one of the inside pockets on one side(in fact it was designed for that.
I have been thinking about buying another one to put in my other pocket to pack a full survival kit in. I think the entire D.R. kit would fit inside with a lot of room to spare.
That would let you put a survival blanket and a couple of baby bottle liners inside(The liners, I would probably put inside the security pocket to protect them).
There is a mesh zipper pocket that is big enough to hold the whistle, compass, sparklite, etc...