In a recent update to the HSBC app they’ve added a screen to prevent you from using the app unless you use the default (google) keyboard.
They do a similar thing if you have an accessibility service running that can access the screens content. A fair enough security warning if you’ve happened to install a dodgy keyboard app, but highly frustrating when using an open source alternative that enhances the security and privacy over the default option (HeliBoard in my case).
I haven’t found a way to circumvent the page yet. It would be useful if Android allowed you to block the permission to query all packages, but alas.
Can apps has their own keyboard and never call the system one? Installing their kb as another app and as a system one at that would be 200% more infuriating. Now THEY can log your keys elsewhere.
They can build a keyboard into it, sure. It’s just UI elements and a bunch of buttons. Won’t be a good keyboard, but it can be done.
It’s possible. First example I can think of is NYT’s games app uses their own keyboard. It’s clunky, but if someone is concerned (or data hungry) enough for the users security they certainly could.