About the pattern on the shirt .
I'm not sure this is the technique used, but I have seen once a demo
1 aerograph an almost white green on all the surface
2 Use a canva ( medical gaze ) dipped in a mix of water and glue for wood, apply on the surface
3 make your camouflage pattern all over it with aérograph
4 take the gaze away
Best
I don't like busts but I recognise amazing painting when I see one