Closest would be Google's Android Flash Tool that uses WebUSB to image an Android phone. But that is more like a browser extensions versus a HTML5 application.
I have had numerous experiences with ZScaler, corporate man-in-the service, breaking web sites with Firefox. I need to use Chromium to upload to Virus Total. ZScaler even likes to brake web sites on Chromium and requires multiple reloads with minutes or hours between refresh.
Microsoft services with ZScaler break easily with Firefox and Chromium but work fine with Edge or MS Teams. Don't know if this intent to push users to Edge or just a correlation with ZScaler.
ZScaler developers, thanks for making my work life living hell with 30s or more latency and lack of ability to properly connect to web services and handle cross-VM HTTP testing.
This is not the only case btw, just a nice clearcut one
This comment keeps popping up. Every time I ask the commenter to show me some sites that dont work with Firefox. Nobody has ever shown me one. I think people are stuck in the past here, Firefox has been absolutely fine for about 10 years now.