Sort of. I think this is based on the `registerProtocolHandler()` means, and if so, you can redirect this to an internal page in your extension. See https://addons.mozilla.org/en-US/firefox/addon/overbitewx/ (disclaimer: authored by yours truly).
The more pressing concern is how you would speak these protocols because there's still no direct socket support. In my case, the addon just acts as a history and redirect shim and my server does the actual server access and translation. I'm actually thinking of cobbling together a native messaging-based extension as a stopgap since obviously this is suboptimal.
Hi, I did just like you said using Native Messaging API[1] to communicate with a local companion app using standard input/output shell calls, this app can handle the socket communication, that is how I am handling it for the scuttlebutt experiments I am doing (I mentioned them above with some URLs if you want to check), I hope to start a conversation soon on the add-ons list about the needs of having UDP and TCP available for WebExtensions. It is suboptimal but it works today...
The more pressing concern is how you would speak these protocols because there's still no direct socket support. In my case, the addon just acts as a history and redirect shim and my server does the actual server access and translation. I'm actually thinking of cobbling together a native messaging-based extension as a stopgap since obviously this is suboptimal.