The issue isn’t that the functionality doesn’t exist, it’s always backwards compatibility with versions where it did not yet exist.
I'm not saying that npm is doing everything right, but I suspect that beyond the obvious low-hanging fruit that we hear about pretty consistently with npm there's probably a long tail of less obvious stuff that can be exploited that will not be specific to npm. The fundamental problems with supply-chain vulnerabilities aren't going to go away if npm magically became pip or go modules overnight.
Both the Browser and Node.js standard library are fairly extensive. I don't think there's much you can do with other language you can't do with Node.js. And as a lot of newer languages have demonstrated (like zig and hare), you don't need an extensive one.