Unlike iOS, Android doesn’t have the concept of phone vs tablet. See, Apple control exactly what devices their OS can run on - you can’t deliver a piece of hardware to market running iOS because Apple are in control of that.
With Android, the line between phone and tablet are basically non-existent. Anyone can build a device that’s running Android. Many point of sale systems use Android underneath. Sometimes this is a tablet, and other times it’s a phone with an external screen attached.
There’s standard sized devices with a ~5" screen size, but then there’s larger phones up to 6.8" screen size, and foldable devices which extend even beyond this and into tablet territory. Many tablets are also still capable of phone calls - you can fit a sim card into them, and voila - 4G connection and phone call support.
The point to take from this is that there’s no way to limit devices to phones only on Android because such a concept doesn’t exist in an ecosystem that is as open as Android.
This isn’t a limitation of Expo or something that can be fixed by expo. I would be interested in hearing what your specific use case is, as I am sure there are some code-based solutions which could be built using the existing Expo libraries.