In the end, my advice in this case would be to state: "In the interests of being inclusive, if you have strong feelings about what pronouns should be used to refer to you, please put them in your Zoom usernames so we can see them matched up with your name, rather than saying them in your introduction. That will be easiest for people to remember, and we also hope to avoid putting anyone on the spot."

I like this! Question: would the default then be to use they/them for anyone who doesn't state a pronoun preference, and should that be stated as well?