I think this is a really nice idea. I like that it would create extra gameplay with smaller cells fighting over the corpse of a large one. I also like that we have the organelle models so having them hang around and float apart sounds doable.
It ties in with something @Oliveriver was saying about osmoregulation. If we rebranded the current health bar as “membrane health” then it would make sense that when it got to 0 your cell would undergo this type of rupture death. Also if your ATP runs out it would make sense that your “membrane health” would decrease as your water pumps would shut down (even though we don’t have them visibly) and so water would rush in and that would start deforming the membrane, damaging it.
If we did the pilus aswell we could roll that into it, it would make sense if you jab someone it hurts their membrane health. It would also make sense of why it slowly heals over time and why different size cells have similar health bars.
We could give cells with a hard cell wall a really large membrane health bar with strong regeneration but a movement penalty.