Amber isn't a nip07 signing extension.

I've found the best way on Android is Keychat https://github.com/keychat-io/keychat-app It's a browser you can sign into with Amber, and it has a built in nip07 signer.

That's not possible on mobile. Amber works with mobile apps and so it's your browser the one should work with Amber. The closest you can get is by using @bbf923aa…62088f1e