There is a small manufacturer in California, PanTour**, that make a narrow Hub with Suspension in it.
its only 1/2" of motion, but I read of Brompton Owners investing in them.
the suspension motion angle is adjustable , so the brake pads remain over the rim.
I expect there is some buzz reduction. (dont own one, I went for a dyno-hub instead)
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https://www.google.com/search?q=PanT...q=PanTour+bike