I think the only solution is to write each person an email or letter telling them that you don't want material items from them for christmas, what you want is t

I think the only solution is to write each person an email or letter telling them that you don't want material items from them for christmas, what you want is their commitment to spend time with you, or if not that then a donation to a specific charity. You can ask the person to reciprocate, and if they don't confirm then you'll assume they want material gifts. I think something like this would be better on a decentralized keybase where you can set personal public policies like gift acceptance.