Here's a model 6010-800 double-ended flexure pivot from Riverhawk Company
. It's about 8mm (0.3125") in diameter and 12.7 mm (0.5") long. The specified stiffness is 0.0036 pound-inch per degree. That's 0.0004 Newton-meter.
This means that, at a typical tonearm length, it would take about 0.18 gram force to deflect the bearing by 1°. Looks flexible enough for our purpose.
By the way, these flexures are quite expensive. The one we use is more than $100 US, and it's on the cheap side of things! Smaller and softer ones cost a lot more.