Agreed, I will edit the comment

Signal or XMPP are good option

XMPP may be a bit overwhelming as you need to select a provider and a client. Doesn’t require phone number.

Signal is private and easy to use like whatsapp. Needs phone number to use.

Telegram is cool but encryption isnt enabled by default, would like to avoid it for this. Cool for public groups.

Edit: Teleram isnt good at all, dont use it. Look reason in the replies

I dont know much about writing stories/poetry, but for publicity in fediverse (I assume you meant in fediverse too) here would be my response:

Lemmy is good but the main part of fediverse is the mastodon clients (twitter equivalent). Most of the users use a mastodon instance.

So posting to mastodon and lemmy seems like a good option. Although mastodon will limit post text length. Better to repost or boost it from lemmy to mastodon.