There ought to be a built in camera (since a smartphone would be severely crippled without it, making it the only module you'd use) but a module could be something like an upgrade camera with optical zoom lens with a larger sensor.
Also, a battery module of that size wouldn't add much extra runtime. Maybe like 400mAh (about 15% extra) estimating from the approximate size.
Memory module would be nice but probably overpriced as a proprietary form. MicroSD slots would do fine.
There ought to be a built in camera (since a smartphone would be severely crippled without it, making it the only module you'd use) but a module could be something like an upgrade camera with optical zoom lens with a larger sensor.
Also, a battery module of that size wouldn't add much extra runtime. Maybe like 400mAh (about 15% extra) estimating from the approximate size.
Memory module would be nice but probably overpriced as a proprietary form. MicroSD slots would do fine.