Instagram is the default DM platform for young adults in my experience. When I meet new people in non-business contexts they always ask for my IG username (which I of course don’t have).

Depends where you live. Brazil is not Japan.

In non-WhatsApp ubiquitous places, “what’s your IG?” is the standard when you meet someone in the wild. You can always go with “oh, just WhatsApp me!”, but then again you’re still on Meta. I’m talking about age range till like 35ish, probably.

Also, significant chunk of people don’t use Instagram/Facebook for posts, but just like another messaging app. I basically have my notifications enabled for DMs, and not that interested in content scrolling.