All those physics related things are based on custom work I did a long time ago, I published fixed timestepping for 4.15 and later made also contact modifications public for 4.18 so others may benefit from (worth noting that Epic exposed contact modifications partly now on 4.20 but you still need custom engine code to use it - which is what my current changes do now). Basically if you do custom vehicles or other advanced physics and/or physics networking, you often want changes like these to gain more control over physics. As for using GameWorks itself, I don’t really use it on any project atm, I do these merges for testing purposes only. I keep updating these repos nowadays mainly to stay on top of things: to know where GameWorks tech is going and to know what kind of structural changes UE4 has.
HairWorks is at the end of my list to add but I might check if it’s an easy add, no promises though.
I think someone has asked before. VRWorks is pretty much no-go for bigger merges like these, mainly because it alters rendering pipeline from many same places as these other techs and I don’t really have experience nor motivation for rebuilding the clashing parts. I’m fairly certain you could merge VRWorks with select GameWorks techs (like Blast, Flex, Flow) but these would need to be tested on case by case basis. And ultimately, I don’t have VR gear so I couldn’t even test if it works properly so that makes the whole process impossible from my end (as testing often reveals all kinds of issues and I can imagine part would be way more important when dealing with VR).