Alternative to Telegram channel in any federated messenger

Telegram channels are sort of unique in that they combine broadcasting read-only messages and having a full-blown chat, like any other group chat. Is there anything similar in federated messengers? For now I have to split up my single community into a microblog on Mastodon and a group chat in Matrix and this is super inconvenient.

I know you can create read-only rooms in Matrix, but there's no way for people to comment under posts. There's also a beta support for channels in Delta Chat, but there's comment section either.