What do you mean I don’t host it like mastodon would? Are you talking about the “official” mastodon instance, mastodon.social? Because they do exactly what I described above, and you’d have known if you’d just checked https://mastodon.social/about before posting. Just click “moderated servers”. See all the “inappropriate content” that’s listed there? Most of those allow lolicon/shotacon (as evidenced by their defederation of pawoo). It is standard practice, and whether or not you agree is completely irrelevant. That’s how most instances are run, period, except for the free speech absolutists who are also defederated by everyone else for allowing bigotry/propaganda/lolicon and so on.
I know that there’s a tradition of confidently posting on reddit about something you don’t know anything about and acting like your opinion on the subject you know nothing about is Very Important, but this ain’t reddit.
I run a mastodon instance with some friends, and a single user misskey instance for myself because I like it better than mastodon. It’s its own thing, it’s been around since 2014 and it’s very robust and stable. I love being able to format posts, easily customize the instance and write more than 500 characters.
I’m personally not a huge fan of firefish but it also works pretty well and has many of the same features as misskey.