pub fn read(path: Path) -> Result<Bytes> {
      File::open(path)?.read_to_end()
    }

isn't so bad either.

Exactly, and this is in my experience what most Rust code ends up looking like.

It compromises a bit on generality and (potential) performance to achieve better readability and succinctness. Often a worthwhile trade-off, but not something the standard library can always do.

You would actually use a Result type:

  use std::io;
  
  pub fn read(path: Path) -> io::Result<Bytes> {
    File::open(path)?.read_to_end()
  }

Sure, if you are allowed to change the signature, makes it look more ugly than just returning Bytes though