In my understanding linux can list only those devices which it can understand, i.e. for which the drivers have been installed. I think lspci is the command for that.

But how can one figure out if there exists some device in the system for which the drivers are not installed and perhaps some hint about what that device is for and what driver would suffice for it.

I would like to know this info so as to be able to recompile my linux kernel to a minimum and would like to avoid a hit and trial approach.