Yeah, I don't think the extension is workable any more anyway. Browsers keep "innovating" their support for extensions, and unfortunately SQRL never really caught on quite to the extent we all hoped it would, so the interest from various developers seems to have waned and their software has kind of fallen to the wayside.
Steve's SQRL executable for Windows is the only PC software I know to remain working well. I believe the Android app is still functioning, but I don't use it, so I can't be sure. I know the iOS app was still in beta, and not released (you can learn on this site how to join the beta though), but the beta was working the last time I tried it (some years ago.)