Ctrl + "[" , Ctrl + "]" - bring the full path in the left panel or the right panel respectively into the command line (so Ctrl"+"[" and then Ctrl+Enter will bring full file path of the file under the cursor into the command line)

Ctrl + PgUp - move up the folder tree

Ctrl + U - swap panels (so the cursor goes from one panel to another, useful when you operate in 2 folders primarily, saves you an Alt+Tab)

Ctrl + LeftArrow, Ctrl + RightArrow - makes one of the panels larger or smaller

Ctrl + 1,2,3,5 - change panel layout (file name 1 column, file name 2 columns, file name with attributes, file name with more attributes)

etc. There's a lot. Not even mentioning all the plugins built in the last 20 years.

Fun fact: it was written by a 24 yo college student (graduate?..) from Chelyabinsk and was pretty much functionally complete couple years later. The same guy who designed RAR file format and built WinRar around the same time.