I have no problem with 80 lines side by side with vscode taking up half of my 3440x1440 display (so 200px less wide than a single 1920 × 1440 display). Even with the extra space taken up by the github UI, I can't imagine 40 additional chars is a big deal.

Even at 80 I occasionally sacrifice readability for line breaks to keep my company's linter from throwing a fit. 60 does not sound like a good idea to me.