There is no built-in functions for it, but with som math, it's doable.
There are several ways to go.
I think the easiest is to simply start with a sphere, make some rings and
use them to cut grooves using difference(). A little bit of math is needed
to get the diameter of the horizontal groves right, but not much, just basic
Then, use scale to turn it all into an ovoid. Be aware that this will
slightly affect the depth of the grooves as well, but, I assume you aren't
making a real grenade, just a prop, so "squint scale" is probably close
I know that this is not exactly what you were looking for in that it is
definitely not "parametric".
I cheated and drew the pineapple grenade body and the "cutout" portion in
CAD and then "differenced" them in OpenSCAD.
I can send you the STL file or the DXF files if that would help.