This repo provides a small script to load Ryven as a plugin inside Unreal Engine 4, as well as the nodes package. Notice that there are no nodes at all available yet, because I don't know the Unreal Python API well. If you do, please consider contributing.
Using Unreal Engine's Python installation (located in something like <UE4 path>/<version>/Engine/Binaries/ThirdParty/Python3/<your OS>/python.exe), install Ryven
<UE4 Python location>$ python.exe -m pip install ryven
and save this repo to your file system
git clone https://github.com/leon-thomm/ryven-unreal
Then, assuming you have python plugins enabled in unreal, you just need to execute __init__.py from the Unreal Editor via File > Execute Python Script.... This should open a new instance of the editor. Do not close this window if you don't want to lose the content in it.