Faraday bags pass through all frequencies smaller then the holes in the conductor.

If you want total blocking of all frequencies you need a solid conductive surface, i.e. a block of metal, or a bucket of ionized water.

So yeah, whatever you got, you need to test with the transceivers on the device.

But military grade is just gear porn marketing term, you can make a gaussian surface out of house hold aluminum foil for Pete's sake.

I wonder if I could somehow manage to whip up an experiment using the spectrum analyzer on my flipper zero. I would have to push the button while it is in the bag.