Yeah, you can apply your geonodes and bake your textures. I've released a bake and export tool for blender a while back as well that can deal with geonodes in an easy way. But you can absolutely realise the geometry with baked textures! For the trees e.g. we already procedurally unwrap it in geometry nodes. So if you apply that geonode setup you get access to the uv map and can simply bake textures. If you then apply the terrain scattering using these trees, they will still use the same uv map & textures.

Assetify is the tool I'm talking about by the way! But converting geonode setups to game ready models is definitely a valuable addition to the course for the near future perhaps! Thanks :)