What is the SerialPort APIs for Firefox and Edge?

I’m using https://developer.chrome.com/apps/serial to make an internal webapp to talk to a Chrome Extension that talks to a serial device we have.

Does anyone know what are the relative Serial Port APIs for Firefox and Edge?

Controlling a Firefox extension icon location

The extension’s icon appears always in the top right corner of the toolbar.

I need to place my tool’s icon near the pad lock icon in the address bar as shown in the image below.

enter image description here

There is a legacy extension (not written in Webextension API so I can not really learn from it) that placed it somewhat near the padlock icon but not exactly (I need it in the exclamation mark position).

enter image description here

My question is: how to place the extension’s icon just next to the padlock icon (preferably to the left instead of the exclamation mark but if not possible the to the right or same is the legacy extension example).

If not possible in Firefox extensions, is this position possible in Chrome extensions?

On click copy the html input variable and attributes to clickboard

I was trying to write an internet browser, generic if possible, extension that will help me copy the html input filed and its attributes, of my choice, on click event to click board. Could you give me some directions on this.

Thanks.

Is there any way to check if an Add on is installed or not in Firefox using Javascript?

I have developed an Add on for Firefox and my website works with the add on as a pre requisite. I need to check programmatically whether the Add On is installed or not and if not ask the user to install the add on.

I am not able to find a way how to check this operation of whether my add on is already installed in the user’s browser.

Any help is highly appreciated here.