What characteristics of life to pre-cells exhibit, and which are they lacking that cause them not to be true cells

Could humans ever get to a point where we could photosynthesize?
Going through the lecture and looking at the various nutrition types for protists we have autotrophs, heterotrophs and mixotrophs got me thinking about how humans obtain nutrition.

Autotrophs can produce their own food (via photosynthesis), heterotrophs must consume/ingest their food, and mixotrophs can do both.
As we continue to evolve over the course of thousands/millions of years, do you ever think we will get to a point to where we could produce our own nutrients?
It seems far fetched to think about but this National Geographic article examines some interesting case studies from other organisms.

What characteristics of life to pre-cells exhibit, and which are they lacking that cause them not to be true cells