It's not broken. It expects a browser extension to sign-in. Chrome based mobile browsers don't have that support. So our options are Firefox-based mobile browsers or Nowser, nostr native browser, which is what I ended up going with. That was I can sign-in with amber.
Discussion
How does nowser work with Amber? I can only see nsec entry. Looks like a handy app.
It doesn't work with amber. I used a hex and signed-in that way. I used damus.io/key
wierd, i tried it in firefox, mull(firefox based), and chrome and nothing happened when I hit the button on my android phone.
I use amber.
I haven’t tried nowser yet, I’ll have to check it out.
Be careful with mull, it has been abandoned and no longer receives updates. For a similar privacy based Firefox alternative try ironfox.
You also need a signer extension like nos2x-fox.