I see the FAQ says: "You will currently need the Latest Google Chrome Browser", but the blog says "The key elements are you need to have a PWA compatible web browser (Right now that’s Chromium and Chrome, but the other browsers are all planning to support this )."
So the Vivaldi browser should work (see instructions
here); Vivaldi is an excellent browser and is a pretty good answer to the "spyware" objection. Of course trying to respond to the "pointless" objection is ... well, you know.