This was for a college canteen, and they use Google sites for all of their website work. Would Google sites provide a unique link for the menu after I publish the menu?

Putting that link in a QR code was the original plan, and that QR code would be stuck to a tactile plastic paper, so blind people can figure out where it's located.

Making a page on your website will be helpful and making a qr code that can lead to it can be helpful. Make sure to write the html simply and accessibly and you should be good. Braille menus are optional but so much of that is so expensive and not always cost effective.

in my personal experience, outsourcing this sort of thing leads to delays and complications. If you are big enough that you have an online ordering system, it should be accessible to begin with. If you're a small place, you simply need a usable online version of the menu, QR code is a good way to get at that nowadays, and optionally hard copy in larger print or Braille if you have the resources to acquire those.
Accessible online version needn't be complicated, almost anything that isn't a picture of a board will do the job. A google doc at a push, although I've seen tonnes of places integrate with Google Maps for menus, so whatever they take as input would presumably also work for people needing to read it using something other than their eyes.