Kinda like Medium or WordPress (the .com variant). Gives you your own subdomain and lets you blog. Their policy is that they absolutely will not editorialise anything. It's used by a lot of reputable good bloggers too
You can do that. But certain voices carry extra weight within communities.
I followed today's Formula 1 race on both Threads and Mastodon. Both platforms allow you to follow topics and that's what I did. But then I follow the people I find interesting as well
Aren't there privacy friendly OSes you can already install on your Google Pixel?