I absolutely love ESM modules, pretty much the best thing since sliced bread. Node.js is really botching it, though, with the requirement to use the mjs extension. It makes it very awkward and cumbersome to use the same code in the browser and node.
you not need to use .mjs extension if you setup correctly package.json
I don't want to setup a package.json for projects that don't need it.
Then yeah, you’re out of luck. But the vast majority of Node modules use a package.json so I wouldn’t say Node is “really botching it”, they’re just doing what works for the vast majority of users.