PBR workflow means the diffuse is just color...no lighting information. You can still bake an AO map and engines like marmoset will have a slot for the AO.
I have a question about pbr workflow in quixel. Lets say I grab a texture of window draps. Then I run it through ndo for a normal map and then create a AO based on the normal map. For the diffuse map do I then take out the lighting information of the original image as much as I can?