Access Shape Keys in Geometry Nodes

It should be possible to use shape keys in Geometry Nodes. Somewhat like vertex groups via a named attribute node.

The difference would be that you don't get field weights, but vertex positions (or offsets from the base geometry) as output instead. Is there a compelling reason why that can't be done that I'm not aware of?

If it were possible, this would allow for great ways to add transition effects when blending from one shape key to another or allow rotational shape key transitions instead of purely linear vertex movement (page turning animation with only a basis and 1 extra shape key for example).

The animation of weights would probably have to be done in Geometry Nodes/The Modifier stack. But I wouldn't mind.