Focus the chat input and press Cmd + Shift + Enter. Creating a "text snippet" in this way is not as nice as syntax highlighted fenced code blocks would be, but at least it's easier than uploading a file.
I'd like to politely challenge your assumption that accessibility concerns are relevant only to a "proportionally very small percentage of the population". It's a common myth in this space.
Disabled people represent between 10% and 20% of the world population, and that's not even including those who don't identify as disabled but would nevertheless benefit from more accessible technology. If you've ever adjusted the text size in your browser or enabled captions while watching media, this group includes you.