It seems, that Star Lord from the Guardians of the Galaxy just couldn't use simple engines, because he has no space for a lot of fuel. One thing left is a nuclear reactor. Did he steal them from Stark, or did he invent it on his own like Stark did?
Please don't jump to conclusions which are made up on assumed/opinion based stuff, like you think the shoes have a mini reactor and concluded that Stark is bound to be related somehow, please hold your horses.
Coming to your question, Notice how Quill's quad-blasters, mask or translator did not surprise you which are a marvel themselves and whose features will surprise you.
In MCU, Quill is the son of Ego, a celestial and brought up by ravagers, notice that the Ravagers know this and try never to harm him or let him be harmed in anyway as they know what a celestial can do if he's angry.
Well, Ravagers are thieves, pirates and whatnot, they travel all around the galaxies and their loots often include fancy tech items apart from units (money).
w.r.t MCU, there is no backstory for how Quill got his boots (or anything) but I'd say Ravagers looted a lot of stuff over time and Yondu gave his best to Starlord, the son of a celestial. Also, there is a possibility that Ego gave some items for Quill so that his son remains safe. (To Yondu while Quill was young).
Regarding technology, you never know which planet has what technology until shown in movies,we fans can't predict what tech can be seen in future, we enjoy the tech without going into much logic!