There's nothing that covers interactions between all of them AFAIK, as there are so many of them and their development changes the interactions over time.
Usually you can follow accounts anywhere from Mastodon, and reply to posts too, but if there are features in the platform that Mastodon doesn't have then you won't be able to access those.
Best way to test is to paste an account's Fediverse address into the search box on Mastodon and see what appears: https://fedi.tips/whats-my-accounts-address-how-do-i-follow-other-peoples-addresses-how-can-people-follow-my-address/