If you select ‘Forum Discussions’ under ‘What type of content do you want to see or share?’, NodeBB, Lemmy, mbin, Piefed and Lotide are then recommended. That fits well.

But if you select ‘Social Media Post + ’Forum Discussions", Mastodon, Misskey and other microblogging services are recommended, as well as Lemmy. But not mbin, which actually offers exactly this combination, and also not Friendica, which can do micro-/macroblogging, but also offers forums/groups and federates best with both directions.

So it’s perhaps a little under-complex, but nicely done and a good new contact point for interested people.

Is this like Tumblr or something?

I think Misskey and its forks are among the Fediverse services that are not modelled on a specific commercial platform, but have created something completely their own.

The forks differ in details (see comparison), but the user experience is relatively similar.