Is there any way with Geometry Nodes to get outward-facing Normals?
Using the Geometry generators, e.g. Cylinder, Icosphere, etc? They should be outward-facing by default. Show us your nodegraph, and the result you’re seeing with inside-out normals?
Thanks but I need to find out somehow. I have a Bottle and want to separate the inner part.
Okay: you need a query that selects interior faces.
Geometry Nodes has a “raycast” primitive that can get you part of the way there. Cast a ray from (just off the surface of) each face, towards the rest of the same object’s geometry. If you hit another face, then the querying face is pointing at itself.
https://i.imgur.com/bXmPqvu.png
Naturally, has issues with rays casting out through holes (see the bottom inside of the bottle) or with other forms of concavity. But it might get you part of the way to a solution.
Was hoping there would be a solution not including Ray Casting. 
You asked how to retroactively query inside-ness on an arbitrary mesh. Ray casting is one way. If you’re not sharing why ray casting is undesirable, and you’re not sharing how you generated the mesh, what else could anyone tell you?
I understand your point but don’t have anything to share, also I find Ray Casting overkill.
The Mesh I created by hand. I have managed to get it mostly right using Dot Product of Normals from it’s position however I have to tweak the ramped parts …
If the bottle is made with GN, you don’t need to separate inner part, you can store parts of mesh selections from an extrude node as an attribute.
Thanks good idea. The inner part is to form a Liquid mesh or other filling.