You’re 100% right that right now he is at the “mercy” of his family to help control his environment as opposed to an older person or child having more tools to control their environment. Even a 6 year old can choose to leave a noisy area and go play in their room or seek a quiet less busy spot on the playground - but a two year old if still very people dependent for everything!
No need to search for a “label”. But keep being cognizant of his behaviors and needs and keep everyone caring for him on the same page so there can be consistency for him and all his caretakers! It also doesn’t hurt to share any concerns or “hmmm’s” with people like his pediatrician, child care providers - any others who can assist him or the people in his life!
And since he seems to be pretty verbal (both expressive and receptive?) maybe establish a couple of conversation comments that give him the opportunity to express his needs or discomforts.
“Grandma is checking in with you. Is there something your body needs right now to feel happy?”
Also help prepare him for transitions in environment: inside to outside, warm to cold, one house to another house - just use conversation to give a “heads up” that his environment is going to change soon.