My hemo is part of a cancer clinic and just my opinion from 12 years there- my doctor doesn't accept gifts and it appears that no one does. He likely feels its unethical for him to accept a gift- hey he doesn't even like being thanked! He deflects it. But just what I've noticed at this particular cancer clinic, is when people bring in flowers, the flowers are set out on the front desk for the patients and everyone to enjoy. Or if its candy, baskets of fruit, it goes onto the back desk infusion room for the patients to eat the candy, fruit and enjoy the flowers. Also I think because of Covid they might not allow open boxes of candy, not sure but I noticed all the candy they have out is individually wrapped.
I think doctors might appreciate patients who write positive reviews on Yelp and online review sites.? That might be a way to express your appreciation or like Mel mentioned, a thank you card. Just my thoughts, sounds like you have excellent medical care.