Creating text graphics from a data feed
The obligatory ffmpeg answer (not a very good one, other answers still needed):

You could feed your video through ffmpeg -vf drawtext=textfile=onscreen.txt:reload=1

With whatever other drawtext options you need to put your text where you want it, with the font you want.

reload=1 makes it check the text file for changes every frame, but doesn't give you a way to update the formatting, screen position, or anything else on the fly.  (and you'd have to build your own custom thing to render your data into line-wrapped text.  You could maybe control the on-screen position with leading spaces and newlines.)  And -vf drawtext isn't very nice to use anyway.