Great, Mark, thank you very much for explaining things.
This helped me a little. I am happy that I am not the only one classical developer who is confused by Wolfram's product structure. (Sometimes I thought I am too old (66) and meanwhile too stupid to understand that :-) )
But the question remains: Which of the many environments would be feasible to develop large projects? Programming Lab is definitely not a solution, since it has no idea of "projects" or the like. There are just stand-alone notebooks - maybe linked by manual hyperlinks. If I imagine to develop and deploy some large project with some millions of lines of code, some hundreds of files and some tens of developers and domain-specialists and all their domain-specific reports: It would be a nightmare.
Anyway: Fortunately I am no longer in this kind of business. I am now working with Wolfram just for fun. With pretty tricky algorithmic/mathematical problems, but no more with huge real-world-projects. This kind of things can be solved within some large WL-notebook.
