I will have two questions if you do not mind:

a) Did you use any library other than OpenStreetMaps on this project like a framework or anything else? Or did you code the whole thing from ground up?
b) In total, how much time did you need to attribute to this project to finish it? Would you be able to show me the ropes if I get stuck somewhere, especially in terms of OpenStreetMap integration?

I’m asking because I recently finished a web development course and I am trying to further develop my skills by creating small projects that I’m interested on so that I wouldn’t get easily frustrated and bored. Thus, I want to create something similar to your project but instead of videos, I want it to fetch the data from different websites so that people could see all the available apartments for rental and buying options. For example, if someone is looking to buy an apartment in Spain, they would be able to just go there on the map and see the possibilities through data aggregated from different sources like this, and if they zoom in, they would be able to see specific cities and more options. I actually saw a concrete example for what I’d like to accomplish but it was only for rentals and limited to Ukraine on a page called LUN.