There seem to be several constructions of fundamental group for schemes and stacks: by Grothendieck, Nori, Noohi, Esnault-Hai, Vakil-Wickelgren, perhaps others as well. I am trying to understand the relationships amongst them.

I have begun to look at their papers and can see some of the interrelations which their prefaces often lay out very well. Still I wonder if there is a relatively comprehensive bird's eye view of the landscape that can orient my reading and understanding as I delve deeper.

If it's too involved to sketch here as an answer, is there a survey article I can look at? Do the monographs of Szamuely or Borceux-Janelidze contain it?

There seem to be several constructions of fundamental group for schemes and stacks: by Grothendieck, Deligne, Nori, Noohi, Esnault-Hai, Vakil-Wickelgren, perhaps others as well. I am trying to understand the relationships amongst them.

I have begun to look at their papers and can see some of the interrelations which their prefaces often lay out very well. Still I wonder if there is a relatively comprehensive bird's eye view of the landscape that can orient my reading and understanding as I delve deeper.

If it's too involved to sketch here as an answer, is there a survey article I can look at? Do the monographs of Szamuely or Borceux-Janelidze contain it?