Duplicate the object. Apply a shrink wrap modifier. Then use the shrink wrapped version as the final shape key. To do this select the shrink Wrapped first. Then shift+select the original object. Then on the properties editor->Mesh/Data tab->Shape Keys panel-> click the plus to create the Bais. Then click the drop down arrow on the right and click New From Objects. If you have multiple stages or forms create all of them first then select all and shift+select the original last. Then do this and it will create a shape key for each object. I don’t remember if it uses the objects names as the shape key name or not. So you may want to name your shrink wrapped object before doing this just incase.
I look for it, but there is a YouTube video on how to get this effect using GeoNodes, but it is an older version of Blender so I’m not familiar enough with GoeNodes to know if it’s still relevant. I’ll post it here if I can find it.
