No, Firefox Dev Tools is a completely seperate project historically. Firebug version 3 and up built on top of it, but that’s the only connection (beyond commonality in tool function).
They're sadly moving towards interoperability/feature-parity with WebExtensions, but I don't think they'll change entirely at any point.
I think they've explicitly stated that they're planning to entirely remove XUL from the codebase, eventually.
Presumably that won't mean that Firefox will only install extensions from the Chrome Web Store, though. addons.mozilla.org will continue to exist.