There isn't a way to automatically add spans for arbitrary functions in Node, no. There's currently a proposal to add some stuff that makes creating the span easier to make it auto-closing based on scope.

FWIW the philosophy here is that observability is a part of the application rather than something separate. That's distinctly different from the APM philosophy, which is that a separate process "does the observability" and your app is "clean" from that. I think there's quite a benefit to manually instrumenting in your codebase intentionally rather than having an automated process do it for you. But I can understand not wanting to go through and do that.