This has been a huge work in progress for me. I would say that the landscape shader/material was and is the most challenging part of this process so far. I am still working on it and will continue working on it for a while. Right now I am using/dissecting Auke Huys shader material that he so graciously shared with everyone in the Unreal Forums.
Thank you Auke, you are a genius and we don't deserve you!
If you like this check out Auke's stuff, he's gads better than me!
https://gestoryscht.artstation.com/