Here's confirmation that it doesn't (from the site's FAQ via its menu at the top right):
> What devices does this work on?
> You can practice with Interview Warmup on the latest versions of Chrome on OSX, Windows, and Android, as well as the latest version of Safari on iOS devices. Firefox and iOS 14.4 are not currently supported.
This is Ceasar Chavez on Easter Sunday. The ego of people at Google is larger than their intelligence. They don't understand when they turn people off by their "smart" decisions.
I had to google "Ceasar Chavez on Easter Sunday" to find out what you are talking about. Seems like a storm in an easter egg. I 100% see why google would prefer to celebrate a national hero instead of celebrating a religion that a portion of the population care about.
Chrome has 3.4B users. Safari has 1B. Edge has 212M. Firefox has 180M. Not that surprised a small unique page like this only supports the top two browsers.
It should definitely be messaged in the UI, but firefox unfortunately wouldn't support this webapp at the moment.