I am not from the area but the deliberations about which messaging platform is kosher are an enormous time waste for every bottom-up organization, especially FOSS projects or hacker spaces.
As a Finn, I've definitely had to say the phrase "No, I don't have WhatsApp" more times than I care to count. That being said, I imagine a FOSS project or hacker space to be more cognisant of WhatsApp's ownership than a car dealership trying to sell me a used car via video call. I got rid of my WhatsApp precisely because Meta started tweaking the terms of service.
Interesting you think it's less important for "FOSS projects". I would think the chat should be free software especially in those circles. IRC, XMPP, Matrix, email. Lots of options that have been around for decades now.