Can i get covid19 in my tiny backyard? if a neighbour has it, can the wind carry it over the fence to my courtyard? what about parks if there is a 10m+ distance from people?

Many things possible: Many things are possible in life. People get COVID-19 viruses by breathing them in, or transferring them to their eyes, nose, or mouth through touching. It would seem impossible to get infected if you were inhaling 3-meters-upwind from a sneezing, coughing COVID-19-infected backyard barbecue. If you were downwind from them at a 3-meter distance, infection might be more likely. 10 meters is far.