I mentioned the chips because I had some success with using the earlobe chips as constraint for earrings.

But easier soluton: If you give all the vertices of the button the same weight in the weight maps, would that not make them rotate as an undeformed body around the joint centre? Morphs are just linear translations and they could be copied from the 'anchor' vertex.

For behaviour like in dynamic cloth an object needs more than one vertex to follow or the direction would be undetermined. (vertex has 3 coordinates, object has 6 degrees of freedom). Even following the normal in addition would only give 2 more parameters and leave rotation of the button around the 'shaft' undetermined. You would need to maintain orientation with at least one other vertex, but better with a few more and average out. That could be doable with an addon, sort of 'sticky'objects server, Garment comes with an 'on-load' script that registers the buttons with a pointer to the vertices they connect to. The button needs not be a separate object but that could be more convenient to manage them.

maybe, one day, when the moon is in the seventh house and Jupiter aligns with Mars ...