I had a similar experience as you. I finally decided just to figure it out myself.
This is far from perfect, and is very much a work in progress, but this should help point you in the right direction:
Also I’ve come to the conclusion that it is 100% impossible to “not modify base Lyra code”. There are bugs. There are massive numbers of classes that you’ll need in C++ that are not exported. There are private scoped variables with “allow blueprints to modify private” meta uproperties that spectacularly fail to consider derived C++ classes as a possibility.
You will be forced to modify Lyra code. Just try to do the bare minimum modifications as necessary, that is my goal. That means I’ve copied all the Lyra blueprints, Data Assets, etc to my own project to modify them. It also means I’m extending C++ code in my own project and adding the functionality that I want to those classes (but again I’m forced to export Lyra stuff and/or change variable/function scopes in some cases).
A lot of what I’ve done isn’t documented on that site, but the starting steps are there. Hopefully it’s enough to point you in the right direction.
Good luck. 