> We have actual issues at play hereThe only actual issue in play for you personally is COVID, and I've already said I agree with your judgment about the "COVID is a hoax" belief being a lie. My point about "unreliable sources" was not that your particular judgment about COVID was wrong; it was to try to get at the root cause of why your belief is so dramatically different from your family's, and why I think it will be so difficult to get them to change.
However, I am perfectly willing to give specific answers to the specific questions you ask:
> do I go to New Years celebration or not with my family?
Based on what you have described, I wouldn't go if I were in your place. My wife and I have refused to participate in some gatherings with her family for much the same reasons (their belief is not as extreme as "COVID is a hoax", but we are not confident enough in them taking the proper precautions to risk it, particularly as my wife already has some chronic health issues).
> Do I follow them to Disney World next month?
Same answer as above. (Note that in this case, you also have to worry about how reliable other people at Disney World are at taking proper precautions.)
> How much should I work to convince my family that flying on an airplane is a bad idea?
Based on what you've described, unfortunately I think you have very little chance of succeeding between now and next month, so to me it's more a matter of how much risk of permanently alienating your family you are willing to take in an attempt that will almost certainly be futile.
Why do I think you have very little chance of succeeding? Well, that's what my discussion about sources of information was about. You think the problem is to convince your family that "COVID is a hoax" is a lie. But I think your problem is much harder: to convince your family that the sources of information they trust are so unreliable that they should stop trusting them and start trusting the sources of information that you trust instead. Which is going to be a very heavy lift since the sources of information you trust have also told lies.
It's possible that you refusing to go, and explaining why, will move the needle some.
> Do I just watch them recklessly endanger their lives to see Mickey Mouse?
I'm very sorry that you find yourself in such a position, and I'm also very sorry that I don't have any good ideas for how you could stop them between now and next month. Unfortunately, for the reasons I have given above, I don't have any such ideas, other than refusing to go yourself and making sure to explain to them why you are refusing.