I recall UDK had training materials about baking scenes (lighting/textures/etc.) for mobile platforms. Are there any tutorials about baking (non)directional lightmaps with (and without) specular component in UE4 ?
Also wondering if there is a way to not author normal/spec maps when deploying to mobile/VR as norm/spec already baked into directional lightmaps anyway (so having only diffuse and emission maps would save RAM and drawcalls).
Thanks!
You don’t have to do anything extra, it already works.
So, do I just bake lightmaps and deploy to Android and worry not about the details ? 
That’s what I did, I didn’t have to do anything special at all, the materials and lighting looked pretty much the same except more compressed. I don’t think you can remove your normal/spec maps after building, I would imagine it wouldn’t render correctly.
I don’t think it supports non directional lightmaps though, in UDK that was the Lightmap Specular option which I don’t think is there anymore.