You could try some variation on this approach:
Depending on your starting topology, the top 2 modifiers in ths stack are Subdiv, and Decimate. Balancing these two will yield a reasonably jumbled triangulation:
When the dual is taken of that geometry, the result is Voronoi-like.
After taking the dual, this GN group creates cells from it:
- It saves the vertex normals of the intact mesh, which will be needed later
- Then splits the faces and separates them by a fraction, so they won't be welded back together in a later move
- It extrudes the split faces along the saved vertex normals, so their sides remain parallel
- The top faces of the extrusion, and the original geometry faces, are both rounded out by extruding again, and scaling the top faces of the extrusion.
- The original is joined to the extrusion, and welded to it, completing the cells
- The result is Catmull-Clark subdivided in the GN modifier, with a heavy crease on the side-wall edges, so the cells don't separate:
Above is the result, seen from the outside.
The method seems to extend well enough to other organic solids, and it wouldn't be too many steps to a cutaway, although this one is very crude:
In the comments, illustrated with an inside/outside shader:
Variations on this method might be useful for crazy-paving, procedural stone-walling,corn-cobs, etc.