Yes. I have catodon.social added in my account.
However, the thing with third-party use is they mainly support the Mastodon API (which is not ActivityPub), so if a non-Mastodon software implemented it as well, it should work… like in catodon.social and a few other forks of popular fediverse software.
Back to Fedica, I added my catodon.social account through the Mastodon button. (It's similar with brid.gy, I can use my catodon.social account through the Mastodon path.)