Mozilla's position on the Web Serial API and their reason not to implement this in Firefox:<p>"Devices that offer serial interfaces often expose powerful, low-level functions over the interface with little or no authentication. Exposing that sort of capability to the web without adequate safeguards presents a significant threat to those devices. A user deliberately installing a site-specific add-on may be adequate, given sufficiently understandable consent copy."<p>(<a href="https://mozilla.github.io/standards-positions/#webserial" rel="nofollow">https://mozilla.github.io/standards-positions/#webserial</a>)
Interesting and useful from a technical standpoint, but brings all sorts of caveats, including but not limited to security and potential dependency on remote services that the user has no control on.