Misskey seems really popular looking at numbers. I’m confused because nobody talks about it. Is it because of some niche super active audience?

Unfortunately yes.

I’m a minority: I’m using Signal a lot, as well as Mastodon and Lemmy. However I was describing the situation around me and they’re largely using Meta products.

I don’t mind having 2 tools: one for public conversations with strangers and one for family and friends.

WhatsApp has replaced Facebook for family and friends here in France. However, I keep using Facebook due to local groups and town hall posting there.