Not sure if there are any other noobs out there like me, but since all of the recent sample projects reference absolute paths, I was just copy pasting the sample files from the docs to try and make things work, and kept having issues importing key_handler.h
Turns out its not inside $(Astra_SDK_Home)/include, but rather its in $(Astra_SDK_Home)/samples/common, so you have to add that to your “additional include directories” list in VS so it can find it. Probably pretty basic, but posting here so future noobs don’t have to struggle like me.