This is untrue. There are plenty of modules published to npm which don't use node APIs, often specifically so they can be used in many runtimes.
Here's one example: https://www.npmjs.com/package/squat
Here's one example: https://www.npmjs.com/package/squat
So yes, there are plenty of pure JS modules. But if you want to read a file from a disk you’re going to end up with a library that assumes you’re using Node.