Firefox … sends user data to Alphabet inc, NEST and other Google advertising companies

I don’t think this is true. The Mozilla FAQ states that they only use telemetry data for product improvement.

Also, you’re probably aware of this already, but Vivaldi is not open source.

We need a Carl Sagan/Neil Degrasse Tyson/David Attenborough figure too.

That’s unfortunate that Lemmy doesn’t support this yet. Hopefully they’ll implement this functionality someday.