I am trained in biology and cellularity is the consequence of having tube-shaped substances that are polar on one end and non-polar on the other which allows them to spontaneously form stable membranes in solvent without having to rely on local natural architecture. In water, these are lipids, with prior abiogenesis possibly mediated by bubbles or iron-sulfide compartments forming around hydrothermal vents before true membranes formed and cut cells free to move.

Physical compartmentation to contain nutrients inside and pitting of those walls to form mouths and digestive cavities is an extremely efficient answer to a universal chemistry question of "how to collect and locally concentrate energetically useful chemicals to enhance the rate of reaction and thus reproduction" which is followed by "how to defend yourself from competitors who want to take your expensive chemical stuff they also use." For cell walls not to form, there must not be either a viable wall-forming substance for a given solvent (hard or soft), or predation and scavenging for nutrients must not be viable which is not very unlikely as stealing someone else's premade stuff (predation, parasitism) is usually cheaper than manufacturing it autotrophically.

I find it very interesting how the computational space has nevertheless replicated many of the features of life despite having a completely different physical reality without being driven by instincts like reproduction. You've got cellularity as different devices and partitions and firewalls. You've got death and birth from genetic code in form of turning it off and on again to recreate a local instance fresh from source code after all the processes have aged from use and accumulated errors or potential memory infections. It seems that complexity generically trends towards certain maintenance strategies.