I’d suggest opening a topic on the github issues area. They have been pretty quick to respond to feature requests.
I recently struggled with this too. I wanted to provide some code snippets on one of my sites but didn’t want to install a plugin to do this even though I know there are plenty out there, just search “syntax” and they’ll come out of the wood works.
What I found is that the html widget renders conveniently, EVERYTHING, well client side stuff anyway, html css, and javascript. So if you want to add a bit of css or js, you can do that and it renders real time in the preview. But what if you don’t want it to actually render?
I simply ended up converting my snippets into html entities, including the wrapping script or style tags which is an important requirement for this to work and of course placed that inside pre / code tags. I had to add a little bit of css to style it just right but got it looking nicely without all the extra syntax formatting fluff of course.
I’m sure this would have been much easier to just let some other plugin handle this via shortcode, converting each line into span tags and syntax formatting as needed, but I didn’t want to have to babysit yet another plugin to later become un-maintained.