I have a HP 840 G3 that was donated to me to Hackintosh, currently running High Sierra 10.13.6. This should work for the 840 G2 and you may even have more luck with the 840 G1 with the WiFi that PCIe.
My method to install OS X on the SSD from a working real Mac via SSD to USB converter. I then install Clover and add my kexts ad set the config.plist
SD Card reader
Video - screen looks better in OS X then it does in Windows 10
WiFi and BlueTooth working OOO using the below hack
Battery status with Rehabman's DSDT patch
Sounds - using VoodooHDA
Microphone - cannot turn it off or mute
Keyboard backlight - controlled though BIOS anyways
touchpad - using VoodooPS2Controller
USB3 - this laptop has two on board only and I haven't test them using the docking station
Ethernet - using IntelMausiEthernet
Sleep - kind of, closing the lid doesn't go to sleep but goes to sleep over time.
This laptop does not have a Webcam - enterprise model.
Finger Print device
For me what keeps this from being a day to day usable laptop (Mac Book) is the WiFi + Bluetooth, not having battery percentage could be an issue later though.
-removed title instances of Files
-removed title instances of macOS
-minor updates to "hotpatch" section
-added thread history section
-removed NOTICE: section, it is outdated
-added 10.14 to thread title
-added 10.14 to thread tags
-added artur_pt to Thanks list for being the first person to try to help me 4 years ago.
-FINALLY removed the [WIP] in title. I think it's safe now, haha
-HUGE post cleanup! should be (hopefully) easier to navigate
-added new section for 10.13 High Sierra
-added link to Andrw0380's 10.13 files
-removed old link to Andrw0380's 10.12.1 / 10.12.2 beta files
-updated link to Andrw0380's updated 10.12.4 files
-updated thread title, now shows 10.8.5-10.13.x
-removed images as they weren't loading anymore anyway
DISCLAIMER: I can be in no way held responsible for any damage to your computer as a result of the information or files provided on this page. I can't be held responsible for the faults and errors of those who follow (or choose not to follow) my advise or instructions. You are on your own if you proceed. This was created with the assumption that anyone following it would be using the SAME machine model and hardware setup as mine, a HP ENVY 17t-j000 Quad. Using any other model or hardware configuration may work but is completely unsupported! This was never intended to be used as an installation guide and shouldn't be referenced as one. It is merely a place to list my testing results. Consider this your one and ONLY warning. Continue at your OWN RISK...
WARNING: thread history follows: (cloned from post HERE)
RehabMan has been hard at work and has created a much better, more reliable method for both current and possibly future OS X installs. His new method, named the "hotpatch" method is far superior to our old ones and should rightfully take its place. Following is a direct link to his detailed and extensive guide to assist both current and future users with their adventures in OS X. Should you find success using his method, please remember to say THANKS for his work and to possibly add to his growing repository to hopefully assist future users in their own success stories. If you are looking to try on the very bleeding edge, then this is where you want to be.
RehabMan "hotpatch" guide
README: The following files were created using very basic testing to ensure very basic functionality. I cannot possibly foresee or test for every possible setup scenario, so I don't even try to. There may be unforeseen problems or issues that I was unable to expect or resolve. Please try to keep this in mind should you decide to try them out. Hopefully, someone finds them useful. I cannot and do not speak for Andrw0308's specific support files.
REMINDER: An unbelievable amount of hard work, dedication and enormous amounts of time have gone into the making, testing and maintaining of the content for this post, this thread and the entire forum as a whole. Please do try to remember that SOMEONE has to make all this happen. Be sure to THANK those who deserve it. A little appreciation goes a long way.
CONCLUSION: I truly can't believe how long this thread has survived and it is awe-inspiring to see how much further it has moved along since I last visited it. You are all just amazing and wonderful people for doing what you do. You all know who you are.