My understanding is that yes, wrapping an RFID enabled device in foil prevents it from being scanned.

I have used that method for years on potatoes, and have never had one illicitly scanned. I did find a few mashed however.

As to money belts, the best one I've used, so far, is the Blackscout Survival belt. Light nylon, plastic hardware, unique elastic slots on back, allow you to slide in cash,, and other small objects. It doesn't print, isn't dressy, does not stand out as unusual. Comes with accessories that you should omit in certain venues. . Downside is that it a bit pricey.