You owe him nothing. It is that simple – You are no longer responsible for his well being or comfort.
That’s the default attitude.
Now if you want to take a step out of compassion and send him a one line text message or email, that’s ok too, but only if you are ok with him not even answering back or saying thank you.
My advice would be: if it hurts you in any way, don’t contact him. Someone else is now taking care of him.