Welcome to ActivityPub! Nearly all of the Fediverse can talk to each other in some way, the main barrier is that a lot of the apps are in early development and you are fairly limited in how those interactions can take place, but that will come in time. You can follow your favourite users and communities in Mastodon and comment from Mastodon, but you are limited vice versa at the moment.
Edit: I found my Lemmy profile in Bookwyrm, but not much there, and it looks like Pixelfed displays the images you post in your feed. :)
Fun facts, WordPress also uses ActivityPub. WP comprises 43% of the internet.
I have no idea why they are publishing pieces like this, and it’s objectively false. Mastodon had over 60,000 sign-ups in the last week, and my feed is as busy as it ever was. It went from like 4 million when I signed up less than a year ago to over twelve million now.
They finally did it: Reddit made it impossible for blind Redditors to moderate their own sub - r/Blind (libreddit.domain.glass)
Op-ed: Why the great #TwitterMigration didn’t quite pan out (arstechnica.com) en
Things to think about and lessons to learn.