If PHP is your worry…
… I quickly felt distressed from the fact that it seemed to me I needed
to move around a lot of things with PhP or to play with it so to be
able to make the possible changes I need.
… you are going to have trouble with either a child theme or a stand-alone theme. Both are PHP, and a lot of it, though perhaps not difficult PHP, depending on what you are trying to do. Beyond that, I don’t have a general answer for you. If you had a specific question about a specific problem maybe we could get somewhere.