A note for anyone who is thinking of switching from ranger, to customize key bindings you need to recompile the application [0]. The developer is not interested in maintaining custom keybinding support. For more insight into the reasoning behind the current keybindings see this issue thread [1].
Also mentioned in this thread, lf a ranger clone written in go [2].
[0]: https://github.com/jarun/nnn/wiki/Advanced-use-cases#custom-...