Hello together,
we run for chat.sum7.eu already an IRC-XMPP-transport.
So every person is able to join any IRC chat(room) without another IRC client.

IRC-Transport

Join a chatroom #ROOM%SERVERNAME@irc.chat.sum7.eu/MYNICKNAME, by replacing MYNICKNAME with your nickname.
e.g. #card10badge%irc.freenode.net@irc.chat.sum7.eu or #ffhb%irc.hackint.org@irc.chat.sum7.eu

It is only for an IRC server one nickname possible.
A single person could be contact by using NICKNAME%irc.freenode.net@irc.chat.sum7.eu.

We use the software biboumi for it.

By the way irc.hackint.org run his own transport, so you do not have to trust us, to keep the logs safe.
Like #ffhb@irc.hackint.org with your normal xmpp username as nickname on irc.

Be careful, IRC-Transport stores by default logs of the IRC channels to deliver them after you got online again.
(This could be disabled by changing the default settings persistent and history with your client see)

Threema Transport

Update:

• 2020-05-13 Sadly the REST API of Threema changed, to register new IDS. So we descided to shutdown the threema-Transport

Now we start to develop a Threema-XMPP-Transport, it is a really early state.
The current version is deployed at threema.chat.sum7.eu.

If you like to try it add threema.chat.sum7.eu and send her the message generate.
Afterwards, you get could write any person by use THREEMAID@threema.chat.sum7.eu like ECHOECHO@threema.chat.sum7.eu-Bot.

So we like persons which test it and help us to improve the software.
Do not be shy to open an issue under dev.sum7.eu/sum7/thrempp.

For Thrempp we use the library of o3ma and go-xmpp for it.
The current structure of Thrempp makes it possible to add other transports, later.

We hope to support more functions than Threema's personal text, image and audio messages like group chats soon.

Be careful: We store your Threema Privatkey and open any encryption to other threema accounts.
Pictures- and Audio-Files are stored for 7 days unencrypted as XMPPs HTTP-Upload.
It is technically necessary, because the end-to-end encryption in threema and xmpp are not interoperable.