Hi. Long-term HN user based in Helsinki. I'd join but don't really want to share my phone number with a large group of people. Can you not find another way to co-ordinate?
There should be an email sent out whenever a meet is organized. WhatsApp group is mostly for choosing the most suitable date and a place , it’s not mandatory for participation
You don't have a throwaway Google Voice number? I use one for dating apps. Very convenient and worry free.
Things might change in the future, it seems that WhatsApp is gonna start offering usernames, I saw the notice on my app a few weeks back.
That would allow using it with strangers, without sharing a number, in the future.