This is the result you get in two clicks. This scripts allows you to quickly choose an environment texture you like, and apply it to every object in the current document.
http://arsent.ch/athanaze/easy_reflections_video.mp4
Put the "easy_reflections.FCMacro" file and the "easy_reflections" folder in your .FreeCAD/Macro/
Tested on linux only (Kernel: 5.4.31-1-MANJARO) but should work flawlessly on other platforms. Tested on FreeCAD 0.18 stable.
All the environments textures come from https://hdrihaven.com/ and are licensed under the CC0 license : https://creativecommons.org/publicdomain/zero/1.0/