The key to a decent wiggle pick is using "spring" steel that can bend and spring back (I think they use leaf springs from old cars.) A Swing pick from a hardware store is a much heavier tool.
There are two styles, a Texas style that has a longer blade that is used to collapse a vertical dig wall. (Push it down into the dirt and use the handle for leverage to break up clods and work a vertical face.) The Missouri style is made for rocky digs, and I think have shorter blades.
Creek Dalton on YouTube used to make and sell Missouri ones.