I don't see any effect made by this node, I tried many combinations I was able to think of, what am I missing?
What is a proper way to initialize the layer?
Should I create initial metadata somehow differently, and then edit with this node? (but why then...)

houdini 19.0.498

I spotted in Omniverse Create that it is creating attributes on the layer, and after that in the Scene Graph Layers tab in Houdini too. Expected them binded to default prim (maybe that's what happens though).

I think there's no clear question now. Just confusion. Sometimes Scene Graph Details shows the result of a node (rendersettings e.g.), sometimes you'll find it in metadata sub-tab.

you can right click on the node and go LOP Actions - Inspect Active Layer to see the effect.

olegzv
I think there's no clear question now. Just confusion. Sometimes Scene Graph Details shows the result of a node (rendersettings e.g.), sometimes you'll find it in metadata sub-tab.

The Scene Graph Tree is showing prims. Scene Graph Details is showing properties (attributes and relationships) which belong to prims. The metadata tab is showing metadata which can be attached to prims, properties and also layers. Exactly what a lop authors depends on the node. Like frostfx said you can usually inspect the active layer to see exactly what a lop has authored.