So if I had the mastodon app, is there anything I can do with that? Or what would you be signed into to reply back? (Ie) I’m signed into my lemmy.fmhy.ml account, where would I sign into mastodon… tho, I’d like to create another instance to use more like my previous Reddit account
So you would have to sign up for a Mastodon instance to log on to the Mastodon app (I.e. Mastodon.social, mstdn.social, mstdn.es, etc). Similar to the fact that you're signed in to a Lemmy instance right now on lemmy.fmhy.com there are other Lemmy instances such as lemmy.ml, lemmy.world, Beehaw.org, etc.
Your Mastodon account would be completely separate from your Lemmy account.
Does that make sense? Not sure if I explained that we'll.