I use it everywhere I can for the stuff I host.

With how even banks rely on SMS for 2FA these days, I think this stuff just isn't on most companies' radars. It adds some convenience but until whoever is in charge of setting out a road map is convinced this is useful or something users may want, there's little benefit to spending the dev time.

I use my phone for this stuff because Linux doesn't really support this stuff without faffing about with command line stuff and these keys are quite expensive (especially considering you need two to be safe).

It's a shame, really.