shea moisture theirs a baby version you can find it in walmart in the baby section my son is mixed and has the exact hair texture and i like that for his hair the back is constantly getting really dry so i do try and moisturize it and also with mixed babies and curly hair they will need product in their hair (or maybe just my opinion) and your son has curly hair definitely and you can help tame it with curling products to keep cute curls instead of straights (without product also at times the back of my kids hair will be straight until i put product in it) (also im 99% sure his curls will stay just they wont also look as good without product fresh out the bed 😅)
I don't think you need anything for his hair. The most I would use is a little leave in mixed with water in a spay bottle, just for frizz control when needed.