Well, the (relatively) easy way to do it would be to bring it into OBS as a video source. Screen-capture another app that does the typing bit, or physical-capture another machine that does it.
I believe PowerPoint works that way, or at least it did a decade or two ago when I was still paying attention to it. Using dual screens, but not Presenter Mode, you could edit the same slide that was being shown, and the edits would be shown immediately in real time, character by character if you were typing.
Or you could screen-capture a text editor and crop the toolbars in OBS, if you're okay with a blinking cursor.
If you're doing this over the internet and not locally, that opens up a whole 'nother can of worms. In that case, what do you actually receive? That alone could kill this whole idea.
