I read and upvoted other answers, so this is piling on in my own words.
Photosynthesis is only a means of providing energy to convert physical elements and chemical compounds into other physical forms useful for the plant. Put a living plant into an all nitrogen environment, at the same air pressure and with all the sunlight it normally needs, with its roots in some non-nutritive equivalent of soil (e.g. all silica sand), and it will die. It may still try to photosynthesize, but that energy has nothing to break down. Water, CO2, and other nutrients absorbed from the soil are critical to its survival.
Secondly; the first "technology" of the predecessors of homo sapiens was most likely not about food at all. To my knowledge the earliest known use of tools, before any use of shaped rocks, is the evidence that rocks were used as weapons to crush the skulls of same-species individuals: Presumably rivals. We have the fossilized skulls to prove this, from an era in which we have no shaped rocks, and the timeline indicates the earliest of these fossils coincided with about a 50,000 year span of rapidly increasing skull thickness among our predecessors.
Even given the presumption that hunting and farming are not necessary for food in any way, there are many other reasons to settle in a specific area; for example to build an infrastructure that protects one from predators, guarantees easy access to clean water, provides plenty of sunlight and has natural defenses against our own kind (other tribes) that might want to steal it. Also preferably large enough to expand the population.
Every living thing has some form of paradise that makes life easy. In fact, the main reason we did not settle in the first place was a food driven reason (we were hunting and gathering food to support ourselves and our offspring). Chances are photo-humans would settle far more quickly, with no particular reason to walk 20 miles a day, and plenty of reason to just stop and set up permanent residence in the first near-perfect place they found. (or turn it into a near-perfect place by landscape modification; diverting water, clearing away brush, forests and other competitors for sunlight, etc).
Technology and Arts could develop for some of the same logistic reasons it did in humans: Once the food supply is secure (for us by herding and farming, likely in that order), people have idle time to pursue other interests, and some of those other interests will be understanding how things work and exploiting that to make life even easier. Or safer, or more fun, or more satisfying.