Hi Direct-Duck and welcome!
I have to agree that this kind of resource is obscure, not a lot of people talk about it and it’s far from being well documented, if you want to control a shader parameter inside Unity, 3 methods come to mind.
1 : you can use a script to access the parameter and tweak it from there (It takes a bit more time)
2 : you can use an animation using the Animator Module (the downside is that you have tu use the play mode everytime you want to see the effect), or…
3 : you can use for example the texture coordinates node with 4 float parameter (UV is not worth using but W and T are) this is probably the best option most of the time.
I have linked an image showing that in Amplify Shader but i guess ShaderGraph should work too. Don’t forget to enable “Custom Vertex Streams” and add “Custom1.xyzw” inside Shuriken and enable the Custom Data module, after that you can directly modify the values inside the Custom Data module the way you want !