“Also, if you get gaps, you should probably use larger padding when baking AO maps (4 pixels for ex.)” –> it was this indeed
“USD shader (with 3dsmax at least) has an occlusion map where you can put your AO map.”
It seems easier than Blender then. Unless I am missing something, I have to use a Mix Shader to blend with my color but then it get “lost” when exported to USDZ. Only color remain.
Hopefully someone using Blender will help me to figure this out (blending each color with AO on Photoshop is a pain)..