Social chameleons... How do folks handle kids situations where it is not clear if your child(ren) are hiding what they are capable of from their teachers and staff?

One of my DC is not what I call introvert (he is not shy to meet people and seems to get along easily with other kids especially older kids) but he seems to be what DH and I consider a social chameleon and it is causing us to be concerned even though he is only in pre-K. He is the one we had tested for other reasons and stunned us with his results. So we struggle with the idea of acceleration and how to decide how it could potentially work if it came up... Add on top of that, his birthday is literally one day past cutoff - and he looks so average (to the point of even initially fooling the tester).

Our other child is more shy with strangers but if they check out okay and survive her grim scowls, she is more blatant about what she is up to (although we are not sure if she is learning to blend in already even though she is younger than DS). In some ways, to me, she is more introverted and less social than her sibling even though she is much louder in voicing what she wants and will be more willing to fight for her piece.