And, to counter the arguments that "the site tells you that you need WebUSB support": you get to the https://e.foundation/installer/ when you click "Check device compatibility" on the main page. Personally, I'd expect either a check that works in any browser or a simple compatible device list. Why would I need a special browser just to check if I can use this OS?

This is especially strange considering they have the list of supported devices in their docs https://doc.e.foundation/devices

So I think the issue is that the button on the main page is poorly named

What I currently see:

main page -> download and try! -> browse supported devices

lands on https://doc.e.foundation/devices which is a list of models, while

main page -> download and try! -> check device compatibility

lands on https://e.foundation/installer/ the chromium-only webusb page. It could be a better page; instead of showing a scary "navigator not suppored" modal demanding you install a particular browser, it could say the automated compatibility tester requires one of these browsers and your phone plugged in with USB, otherwise here's the device finder page