A Reddit post drew my attention to a new digital mode that uses the OFDM modem code from FreeDV for having keyboard to keyboard chats. It's called FreeData, which I have to say isn't a great name for searching.
As you can see it has some advanced features such as a notification that the other party is typing. Messages are confirmed and the software will re-try until it gets through.
There is a wiki with documentation and an active Discord space to discuss the software. There is also a map which shows Barry, VK3BRT and me looking rather lonely here in Victoria, Australia at the moment.
The software is available for macOS, Linux and Windows. You can download the software, currently in alpha, from the Github project.