Blockchain, how is the search for the nearest peer organized?

Question

blockchain

Who is in the subject, tell me, please!
I'm interested in the mechanism itself and some popular ready-made solutions on this topic.
There are a lot of clients and there is no server - is it possible, as in radio broadcasting, to send a certain "wave" and at the same time listen to the same wave? Suppose, to search for the nearest feast? And how to understand which feast is the nearest? On what protocols can such broadcasting and wiretapping be organized? Will the existing "wave frequency" conflict with other signals?
Thank you in advance!