As I know any local DHT keeps only some of nodes - if the network is small/very small then all nodes, otherwise only some of them (nearest?).
So, when I checked different Golang implementations of DHT (Bittorrent, Node Discovery Protocol and similar) - some of them have functions listing nodes, but as I understand, just from local DHT (which does not guarantee that it will contain all the nodes).
Does DHT (DHT algorithms, PEX extension, etc) allow to list ALL nodes? Something as to list all nodes of the network? My intuition on the DHT algorithms is - they don't support such functionality, but I am not sure (I don't know DHT very well).