You can build it for the emulator. It's straightforward to do, but it requires a lot of disk space and it will take around 40-60 minutes on a high end desktop CPU like a Ryzen 9950X. We don't publish official releases for the emulator at the moment because it's not intended for production use and isn't really a good experience to use. We could start doing it, but it'd add some extra work and we'd be concerned about people misinterpreting what it's meant to provide. Emulator builds don't have the regular security model intact or OS updates, etc.
It ensures requests to your backend are vaguely from actual devices, rather than a bunch of emulators. There's many reasons why developers might want this. It significantly raises the bar for credential stuffing attacks, for instance.
Can't wait until we finally kill hacker culture for good. Everyone and everything will be fully secured. It's going to be beautiful. The nerds can cry about it all day long, but they're powerless to stop it.