@the_spc their username would include Flipboard.com as the domain.
Those users are specifically using the Flipboard frontend to interact with Fedi.
There's also Flipboard.social which is an invite-only Mastodon instance run by the CEO of Flipboard that allows traditional Flipboard users to sign up for a Mastodon specific frontend.
I use the word "frontend" because the way Flipboard has integrated ActivityPub, anyone with a Fedi account can use their original username and domain on Flipboard to post using their UI.
So, you could technically have your fwoof.space account there and post from it. Though, I'm not sure if Flipboard is good for normal users, it's moreso for publishers of articles and papers. So it's probably best to stay here and interact with them the normal way.