Mastodon has a ton of apps and Lemmy app development is going crazy right now. Are there any apps that can use both Lemmy and Mastodon accounts (and preferably Kbin accounts too)? I know the interfaces may need to be different, but the protocols are the same as far as I understand it, so it seems technically possible.
Lemmy is entirely federated with mastodon now. there are many issues still but you can look up a lemmy community by @communityname@lemmyinstance.domain from mastodon and follow it there and then you will recieve all posts from that community in your home feed. if you want to reply to a spesific lemmy post from mastodon (broken on instances running 0.18 but working on earlier versions) you can copy the link from the little rainbow fediverse icon on the top of the post and search it from mastodon, and it will load internally and then you can respond from there.